Track system for traction of a vehicle

ABSTRACT

A track system for traction of a vehicle (e.g., a snowmobile, an all-terrain vehicle (ATV) etc.). The track system comprises a track and a track-engaging assembly for driving and guiding the track around the track-engaging assembly. The track system may have various features to enhance its traction, floatation, and/or other aspects of its performance, including, for example, a lightweight design, enhanced tractive effects, an enhanced heat management capability, an enhanced resistance to lateral skidding (e.g., on a side hill), an adaptive capability to adapt itself to different conditions (e.g., ground conditions, such as different types of snow, soil, etc.; and/or other conditions), an adjustability of a contact area of its track with the ground, and/or other features.

CROSS-REFERENCE TO RELATED APPLICATION

This application claims priority from U.S. Provisional PatentApplication 62/275,944 filed on Jan. 7, 2016 and incorporated byreference herein and from U.S. Provisional Patent Application 62/337,101filed on May 5, 2016 and incorporated by reference herein.

FIELD

The invention relates generally to track systems for traction ofvehicles such as snowmobiles, all-terrain vehicles (ATVs), and otheroff-road vehicles.

BACKGROUND

Certain vehicles may be equipped with track systems which enhance theirtraction and floatation on soft, slippery and/or irregular grounds(e.g., snow, ice, soil, mud, sand, etc.) on which they operate.

For example, snowmobiles allow efficient travel on snowy and in somecases icy grounds. A snowmobile comprises a track system which engagesthe ground to provide traction. The track system comprises atrack-engaging assembly and a track that moves around the track-engagingassembly and engages the ground to generate traction. The tracktypically comprises an elastomeric body in which are embedded certainreinforcements, such as transversal stiffening rods providingtransversal rigidity to the track, longitudinal cables providingtensional strength, and/or fabric layers. The track-engaging assemblycomprises wheels and in some cases slide rails around which the track isdriven.

A snowmobile, including its track system, may face a number ofchallenges while riding. For example, the snowmobile's track may performvery differently on different ground conditions. For instance, the trackmay perform properly on a given type of snow condition (e.g., deeppowder snow) but may not perform as well on another type of snow (e.g.,packed snow). This inconsistent performance of the track in differentground conditions can be inconvenient and/or make it difficult to travelefficiently over different types of terrain. Also, the snowmobile mayhave an undesirable tendency to skid sideways when travelling in a givendirection on a slope terrain like a side hill or other inclined groundarea. A weight of the track system may also affect the snowmobile'spower consumption and/or ride. Excessive heat generated within thesnowmobile's track may cause deterioration and/or failure of the track.

Similar considerations may arise for track systems of other types ofoff-road vehicles (e.g., all-terrain vehicles (ATVs), agriculturalvehicles, or other vehicles that travel on uneven grounds) in certainsituations.

For these and other reasons, there is a need to improve track systemsfor traction of vehicles.

SUMMARY

In accordance with various aspects of the invention, there is provided atrack system for traction of a vehicle. The track system comprises atrack and a track-engaging assembly for driving and guiding the trackaround the track-engaging assembly. The track system may have variousfeatures to enhance its traction, floatation, and/or other aspects ofits performance, including, for example, a lightweight design, enhancedtractive effects, an enhanced heat management capability, an enhancedresistance to lateral skidding (e.g., on a side hill), an adaptivecapability to adapt itself to different conditions (e.g., groundconditions, such as different types of snow, soil, etc.; and/or otherconditions), an adjustability of a contact area of its track with theground, and/or other features.

For example, in accordance with an aspect of the invention, there isprovided a track for traction of a vehicle. The track is movable arounda track-engaging assembly comprising a drive wheel to drive the track.The track comprises: a carcass comprising a ground-engaging outersurface for engaging the ground and an inner surface opposite to theground-engaging outer surface; and a plurality of traction projectionsprojecting from the ground-engaging outer surface. A thickness of thecarcass from the ground-engaging outer surface to the inner surface isno more than 0.20 inches, and a ratio of a widthwise rigidity of thecarcass over a longitudinal rigidity of the carcass is at least 1.5.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a carcass comprising a ground-engaging outer surfacefor engaging the ground and an inner surface opposite to theground-engaging outer surface; and a plurality of traction projectionsprojecting from the ground-engaging outer surface. The track comprisesfirst elastomeric material and second elastomeric material less densethan the first elastomeric material.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; aplurality of traction projections projecting from the ground-engagingouter surface; and a plurality of slide members for sliding against thetrack-engaging assembly. A spacing of longitudinally-adjacent ones ofthe slide members in a longitudinal direction of the track is at leastone-fifth of a length of the track.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Longitudinally-successive ones of the tractionprojections that succeed one another in a longitudinal direction of thetrack differ in height.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Each traction projection comprises a recess defining arecessed area at a base of the traction projection.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; aplurality of traction projections projecting from the ground-engagingouter surface; and a plurality of drive/guide projections projectingfrom the inner surface. A spacing of adjacent ones of tractionprojections in a longitudinal direction of the track is greater than aspacing of adjacent ones of the drive/guide projections in thelongitudinal direction of the track.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; aplurality of traction projections projecting from the ground-engagingouter surface; and a plurality of lateral stabilizers projecting fromthe ground-engaging outer surface to oppose a tendency of the track toskid transversely to a direction of motion of the vehicle.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. The track comprises uneven surfaces projecting from theground-engaging outer surface and having a texture to oppose a tendencyof the track to skid transversely to a direction of motion of thevehicle.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Each traction projection comprises a containment space tocontain ground matter when the traction projection engages the ground.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Each traction projection comprises a containment space tocontain ground matter when the traction projection engages the ground.The containment space of the traction projection comprises a pluralityof containment voids to contain respective portions of the groundmatter.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Each traction projection is configured to scoop andcompact ground matter when the traction projection engages the ground.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. A component of the track is adaptable in response to astimulus such that a state of the component of the track is variable indifferent conditions.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track is movable around atrack-engaging assembly comprising a drive wheel to drive the track. Thetrack comprises: a ground-engaging outer surface for engaging the groundand an inner surface opposite to the ground-engaging outer surface; anda plurality of traction projections projecting from the ground-engagingouter surface. Each traction projection is adaptable in response to astimulus such that a state of the traction projection is variable indifferent conditions.

In accordance with another aspect of the invention, there is provided atrack for traction of a vehicle. The track system comprises: a trackcomprising a ground-engaging outer surface for engaging the ground andan inner surface opposite to the ground-engaging outer surface; and atrack-engaging assembly for driving and guiding the track around thetrack-engaging assembly. The track-engaging assembly comprises: a drivewheel configured to drive the track; and an adjustment mechanismconfigured to change a configuration of the track-engaging assembly inorder to vary a size of a contact patch of the track with the ground.

These and other aspects of the invention will now become apparent tothose of ordinary skill in the art upon review of the followingdescription of embodiments of the invention in conjunction with theaccompanying drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

A detailed description of embodiments of the invention is providedbelow, by way of example only, with reference to the accompanyingdrawings, in which:

FIG. 1 shows an example of a snowmobile comprising a track system inaccordance with an embodiment of the invention;

FIG. 2 shows a side view of the track system;

FIG. 3 shows a perspective view of a track-engaging assembly of thetrack system;

FIGS. 4 to 7 respectively show a perspective view, a plan view, anelevation view, and a longitudinal cross-sectional view of part of atrack of the track system;

FIG. 8A shows a widthwise cross-sectional view of part of the track;

FIG. 8B shows a widthwise cross-sectional view of part of the track inaccordance to another embodiment;

FIG. 9 shows a three-point bending test being performed on a carcass ofthe track along a widthwise direction of the track and along alongitudinal direction of the track;

FIG. 10 shows a widthwise cross-sectional view of part of the track inwhich reinforcements are spaced apart significantly in a heightdirection of the track;

FIG. 11 shows a longitudinal cross-sectional view of part of the trackin which reinforcements are spaced apart significantly in the heightdirection of the track;

FIG. 12 shows an example of an embodiment in which the track comprises alow-density elastomeric material and a high-density elastomericmaterial;

FIG. 13A shows a longitudinal cross-sectional view of the track of FIG.12 and FIG. 13B shows a close-up view of part of the carcass of thetrack of FIG. 13A;

FIG. 14 shows a widthwise cross-sectional view of the track of FIG. 12;

FIG. 15 shows a plurality of higher-density elastomeric materials of thetrack in accordance with another embodiment;

FIG. 16 shows the lower-density elastomeric material forming part of aperiphery of the track in accordance with another embodiment;

FIG. 17 shows a longitudinal cross-sectional view of part of the trackincluding a slide member of a plurality of slide members;

FIG. 18 shows a longitudinal cross-sectional view of part of the trackin accordance with an embodiment in which the track comprises a reducednumber of slide members;

FIG. 19 shows a longitudinal cross-sectional view of part of the trackof FIG. 18 illustrating a spacing between longitudinally-adjacent onesof the slide members;

FIG. 20 shows a longitudinal cross-sectional view of part of the trackin accordance with another embodiment in which traction projections ofthe track have different characteristics to generate different tractiveeffects on the ground;

FIGS. 21 and 22 show a perspective view and a top view of across-section of the traction projections of the track in accordancewith another embodiment;

FIG. 23 shows a longitudinal cross-sectional view of part of the trackin accordance with another embodiment in which a pitch of tractionprojections is greater than a pitch of drive/guide lugs of the track;

FIG. 24 shows a longitudinal cross-sectional view of part of the trackin accordance with another embodiment in which the pitch of adjacenttraction projections is variable;

FIG. 25 shows an embodiment of the track in which the track opposes atendency of the track to skid sideways when the snowmobile is travellingin a given direction;

FIG. 26 shows a plan view of the ground-engaging outer side of the trackof FIG. 25, including a plurality of lateral stabilizers of the track;

FIG. 27 shows a perspective view of a lateral stabilizer of theplurality of lateral stabilizers of FIG. 26;

FIGS. 28 to 32 show plan views of the ground-engaging side of the trackin accordance with different embodiments in which the lateralstabilizers are configured differently on the track;

FIG. 33 shows an elevation view of the track in accordance with anembodiment in which the ground-engaging outer side of the trackcomprises uneven surfaces;

FIG. 34 shows an elevation view of the track in accordance with anembodiment in which the lateral stabilizers of the track comprise theuneven surfaces;

FIGS. 35A to 35D show different examples of formations of a texture ofthe uneven surfaces of FIGS. 33 and 34;

FIG. 36 shows a perspective view of part of a traction projectioncomprising an uneven lateral surface;

FIG. 37 shows a top portion of a traction projection comprising anuneven lateral surface;

FIG. 38 shows the uneven lateral surface of the traction projectionbending;

FIG. 39 shows a functional block diagram of an adaptable function of thetrack in accordance to an embodiment where one or more components of thetrack are adaptable in response to a stimulus;

FIG. 40 shows the traction projections of the track of FIG. 39, thetraction projections assuming a first state corresponding to a firstcondition and a second state corresponding to a second condition;

FIG. 41 shows an embodiment where a stiffness of a traction projectionis adaptable in response to the stimulus;

FIG. 42 shows a material of the traction projections of FIG. 41 inaccordance with an embodiment;

FIG. 43 shows an adaptable member of a traction projection in accordancewith another embodiment;

FIG. 44 shows the adaptable member at an outer surface of the tractionprojection;

FIG. 45 shows an embodiment where a shape of the traction projections isadaptable to the stimulus;

FIGS. 46 and 47 show a portion of a traction projection having anangular orientation that is different in powder snow than in wet/springsnow;

FIG. 48 shows a traction projection in accordance with anotherembodiment where the traction projection comprises a shape-changingmember to change the shape of the traction projection in response to thestimulus;

FIG. 49 shows an embodiment where the shape-changing member comprises anactuator to change a shape of the shape-changing member in response to asignal;

FIG. 50 shows an example of an embodiment of a device within the trackthat transmits the signal to the shape-changing member;

FIG. 51 shows an example of an embodiment in which the track systemcomprises an adjustment mechanism for changing a configuration of thetrack-engaging assembly of the track system;

FIG. 52 shows the adjustment mechanism according to an embodiment inwhich the adjustment mechanism can change the configuration of thetrack-engaging assembly while a length of the track remains constant;

FIGS. 53 to 57 show an example of an embodiment of the track in whichthe track comprises an adjustment mechanism to adjust the length of thetrack;

FIGS. 58 and 59 show an example of a connection member of a connector ofthe adjustment mechanism of FIGS. 53 to 57;

FIG. 60 shows a diagram depicting an adjustment command inputted theadjustment mechanism in order to adjust the configuration of thetrack-engaging assembly;

FIG. 61 shows a diagram depicting a user interface of the adjustmentmechanism with which the user interacts to input the adjustment command;

FIG. 62 shows the user interface of the adjustment mechanism;

FIGS. 63 to 66 show an example of an embodiment of the adjustmentmechanism in which the adjustment mechanism is manually operated;

FIGS. 67 and 68 show examples of an actuator of the adjustment mechanismof FIG. 63;

FIG. 69 shows a diagram depicting a controller of the adjustmentmechanism for automatically generating the adjustment command;

FIG. 70 shows an example of an embodiment in which the adjustmentmechanism comprises the controller and an automatic adjustment systemfor automatically adjusting the configuration of the track-engagingassembly;

FIG. 71 shows an example of an embodiment of the controller of theadjustment mechanism, including a sensor and a processing apparatus;

FIG. 72 shows an example of an embodiment of the sensor of thecontroller;

FIG. 73 shows an example of an embodiment of the processing apparatus ofthe controller;

FIG. 74 shows a diagram depicting interactions between the sensor, theprocessing apparatus and an actuator of the adjustment mechanism;

FIG. 75 shows an example of an embodiment of the actuator of theautomatic adjustment system;

FIG. 76 shows an example of an embodiment in which the controller ispart of a communication device;

FIGS. 77 and 78 show an example of an embodiment in which the adjustmentmechanism is configured to change the configuration of thetrack-engaging assembly using one or more tools;

FIGS. 79 and 80 show perspective and plan views of the track inaccordance with an embodiment in which the traction projections of thetrack comprise lateral stabilizers and a containment space; and

FIG. 81 shows a perspective view of a traction projection in accordancewith the embodiment of FIGS. 79 and 80;

FIG. 82 shows a top view of a traction projection in accordance with thevariant of FIGS. 79 and 80;

FIG. 83 shows a volume of a containment space of the traction projectionof FIG. 81;

FIGS. 84 and 85 show side and top views of the traction projection ofFIG. 81;

FIGS. 86 and 87 show perspective and plan views of the track inaccordance with another embodiment in which the traction projections ofthe track comprise lateral stabilizers and a containment space; and

FIGS. 88 and 89 show front and rear perspective views of a tractionprojection in accordance with the embodiment of FIGS. 86 and 87.

It is to be expressly understood that the description and drawings areonly for the purpose of illustrating certain embodiments of theinvention and are an aid for understanding. They are not intended to bea definition of the limits of the invention.

DETAILED DESCRIPTION OF EMBODIMENTS

FIG. 1 shows an example of a tracked vehicle 10 in accordance with anembodiment of the invention. In this embodiment, the vehicle 10 is asnowmobile. The snowmobile 10 is designed for travelling on snow and insome cases ice. The snowmobile 10 comprises a frame 11, a powertrain 12,a track system 14, a ski system 17, a seat 18, and a user interface 20,which enables a user to ride, steer and otherwise control the snowmobile10.

As further discussed below, in this embodiment, the track system 14 mayhave various features to enhance its traction, floatation, and/or otheraspects of its performance, including, for example, a lightweightdesign, enhanced tractive effects, an enhanced heat managementcapability, an enhanced resistance to lateral skidding (e.g., on a sidehill), an adaptive capability to adapt itself to different conditions(e.g., ground conditions, such as different types of snow, soil, etc.;and/or other conditions), an adjustability of its contact area with theground, and/or other features.

The powertrain 12 is configured for generating motive power andtransmitting motive power to the track system 14 to propel thesnowmobile 10 on the ground. To that end, the powertrain 12 comprises aprime mover 15, which is a source of motive power that comprises one ormore motors (e.g., an internal combustion engine, an electric motor,etc.). For example, in this embodiment, the prime mover 15 comprises aninternal combustion engine. In other embodiments, the prime mover 15 maycomprise another type of motor (e.g., an electric motor) or acombination of different types of motor (e.g., an internal combustionengine and an electric motor). The prime mover 15 is in a drivingrelationship with the track system 14. That is, the powertrain 12transmits motive power from the prime mover 15 to the track system 14 inorder to drive (i.e., impart motion to) the track system 14.

The ski system 17 is turnable to allow steering of the snowmobile 10. Inthis embodiment, the ski system 17 comprises a pair of skis 191, 192connected to the frame 11 via a ski-supporting assembly 13.

The seat 18 accommodates the user of the snowmobile 10. In this case,the seat 18 is a straddle seat and the snowmobile 10 is usable by asingle person such that the seat 18 accommodates only that persondriving the snowmobile 10. In other cases, the seat 18 may be anothertype of seat, and/or the snowmobile 10 may be usable by two individuals,namely one person driving the snowmobile 10 and a passenger, such thatthe seat 18 may accommodate both of these individuals (e.g., behind oneanother) or the snowmobile 10 may comprise an additional seat for thepassenger.

The user interface 20 allows the user to interact with the snowmobile 10to control the snowmobile 10. More particularly, the user interface 20comprises an accelerator, a brake control, and a steering device thatare operated by the user to control motion of the snowmobile 10 on theground. In this case, the steering device comprises handlebars, althoughit may comprise a steering wheel or other type of steering element inother cases. The user interface 20 also comprises an instrument panel(e.g., a dashboard) which provides indicators (e.g., a speedometerindicator, a tachometer indicator, etc.) to convey information to theuser.

The track system 14 engages the ground to generate traction for thesnowmobile 10. With additional reference to FIGS. 2 and 3, the tracksystem 14 comprises a track 21 and a track-engaging assembly 24 fordriving and guiding the track 21 around the track-engaging assembly 24.More particularly, in this embodiment, the track-engaging assembly 24comprises a frame 23 and a plurality of track-contacting wheels whichincludes a plurality of drive wheels 22 ₁, 22 ₂ and a plurality of idlerwheels that includes rear idler wheels 26 ₁, 26 ₂, lower roller wheels28 ₁-28 ₆, and upper roller wheels 30 ₁, 30 ₂. As it is disposed betweenthe track 21 and the frame 11 of the snowmobile 10, the track-engagingassembly 24 can be viewed as implementing a suspension for thesnowmobile 10. The track system 14 has a longitudinal direction and afirst longitudinal end and a second longitudinal end that define alength of the track system 14, a widthwise direction and a width that isdefined by a width of the track 21, and a height direction that isnormal to its longitudinal direction and its widthwise direction.

The track 21 engages the ground to provide traction to the snowmobile10. A length of the track 21 allows the track 21 to be mounted aroundthe track-engaging assembly 24. In view of its closed configurationwithout ends that allows it to be disposed and moved around thetrack-engaging assembly 24, the track 21 can be referred to as an“endless” track. With additional reference to FIGS. 4 to 7, the track 21comprises an inner side 25 for facing the track-engaging assembly 24 anda ground-engaging outer side 27 for engaging the ground. A top run 65 ofthe track 21 extends between the longitudinal ends of the track system14 and over the track-engaging assembly 24 (including over the wheels 22₁, 22 ₂, 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂), and a bottom run 66 of thetrack 21 extends between the longitudinal ends of the track system 14and under the track-engaging assembly 24 (including under the wheels 22₁, 22 ₂, 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂). The bottom run 66 of thetrack 11 defines an area of contact 59 of the track 21 with the groundwhich generates traction and bears a majority of a load on the tracksystem 14, and which will be referred to as a “contact patch” of thetrack 21 with the ground. The track 21 has a longitudinal axis whichdefines a longitudinal direction of the track 21 (i.e., a directiongenerally parallel to its longitudinal axis) and transversal directionsof the track (i.e., directions transverse to its longitudinal axis),including a widthwise direction of the track (i.e., a lateral directiongenerally perpendicular to its longitudinal axis). The track 21 has athickness direction normal to its longitudinal and widthwise directions.

The track 21 is elastomeric, i.e., comprises elastomeric material, to beflexible around the track-engaging assembly 24. The elastomeric materialof the track 21 can include any polymeric material with suitableelasticity. In this embodiment, the elastomeric material of the track 21includes rubber. Various rubber compounds may be used and, in somecases, different rubber compounds may be present in different areas ofthe track 21. In other embodiments, the elastomeric material of thetrack 21 may include another elastomer in addition to or instead ofrubber (e.g., polyurethane elastomer).

More particularly, the track 21 comprises an endless body 35 underlyingits inner side 25 and ground-engaging outer side 27. In view of itsunderlying nature, the body 35 will be referred to as a “carcass”. Thecarcass 35 is elastomeric in that it comprises elastomeric material 38which allows the carcass 35 to elastically change in shape and thus thetrack 21 to flex as it is in motion around the track-engaging assembly24. The elastomeric material 38 can be any polymeric material withsuitable elasticity. In this embodiment, the elastomeric material 38includes rubber. Various rubber compounds may be used and, in somecases, different rubber compounds may be present in different areas ofthe carcass 35. In other embodiments, the elastomeric material 38 mayinclude another elastomer in addition to or instead of rubber (e.g.,polyurethane elastomer).

In this embodiment, as shown in FIGS. 8A and 8B, the carcass 35comprises a plurality of reinforcements 45 ₁-45 _(P) embedded in itsrubber 38. These reinforcements 45 ₁-45 _(P) can take on various forms.

For example, in this embodiment, a subset of the reinforcements 45 ₁-45_(P) is a plurality of transversal stiffening rods 36 ₁-36 _(N) thatextend transversally to the longitudinal direction of the track 21 toprovide transversal rigidity to the track 21. More particularly, in thisembodiment, the transversal stiffening rods 36 ₁-36 _(N) extend in thewidthwise direction of the track 21. Each of the transversal stiffeningrods 36 ₁-36 _(N) may have various shapes and be made of any suitablyrigid material (e.g., metal, polymer or composite material).

As another example, in this embodiment, the reinforcements 45 _(i), 45_(j) are layers of reinforcing material that is flexible in thelongitudinal direction of the track 21.

For instance, in this embodiment, the reinforcement 45 _(i) is a layerof reinforcing cables 37 ₁-37 _(M) that are adjacent to one another andextend generally in the longitudinal direction of the track 21 toenhance strength in tension of the track 21 along its longitudinaldirection. In this case, each of the reinforcing cables 37 ₁-37 _(M) isa cord including a plurality of strands (e.g., textile fibers ormetallic wires). In other cases, each of the reinforcing cables 37 ₁-37_(M) may be another type of cable and may be made of any materialsuitably flexible longitudinally (e.g., fibers or wires of metal,plastic or composite material). In some examples of implementation,respective ones of the reinforcing cables 37 ₁-37 _(M) may beconstituted by a single continuous cable length wound helically aroundthe track 21. In other examples of implementation, respective ones ofthe transversal cables 37 ₁-37 _(M) may be separate and independent fromone another (i.e., unconnected other than by rubber of the track 21).

Also, in this embodiment, the reinforcement 45 _(j) is a layer ofreinforcing fabric 43. The reinforcing fabric 43 comprises thin pliablematerial made usually by weaving, felting, knitting, interlacing, orotherwise crossing natural or synthetic elongated fabric elements, suchas fibers, filaments, strands and/or others, such that some elongatedfabric elements extend transversally to the longitudinal direction ofthe track 21 to have a reinforcing effect in a transversal direction ofthe track 21. For instance, the reinforcing fabric 43 may comprise a plyof reinforcing woven fibers (e.g., nylon fibers or other syntheticfibers). For example, the reinforcing fabric 43 may protect thetransversal stiffening rods 36 ₁-36 _(N), improve cohesion of the track21, and counter its elongation.

In some embodiments, as shown in FIG. 8B, the carcass 35 may compriseonly one type of reinforcement (e.g., the reinforcing cables 37 ₁-37_(M)) or any other selected combination of the above-mentionedreinforcements 45 ₁-45 _(P).

The carcass 35 may be molded into shape in a molding process duringwhich the rubber 38 is cured. For example, in this embodiment, a moldmay be used to consolidate layers of rubber providing the rubber 38 ofthe carcass 35, the reinforcing cables 37 ₁-37 _(M) and the layer ofreinforcing fabric 43.

In this embodiment, the track 21 is a one-piece “jointless” track suchthat the carcass 35 is a one-piece jointless carcass. In otherembodiments, the track 21 may be a “jointed” track (i.e., having atleast one joint connecting adjacent parts of the track 21) such that thecarcass 35 is a jointed carcass (i.e., which has adjacent partsconnected by the at least one joint). For example, in some embodiments,the track 21 may comprise a plurality of track sections interconnectedto one another at a plurality of joints, in which case each of thesetrack sections includes a respective part of the carcass 35. In otherembodiments, the track 21 may be a one-piece track that can be closedlike a belt with connectors at both of its longitudinal ends to form ajoint.

The ground-engaging outer side 27 of the track 21 comprises aground-engaging outer surface 31 of the carcass 35 and a plurality oftraction projections 58 ₁-58 _(T) that project from the ground-engagingouter surface 31 to enhance traction on the ground. The tractionprojections 58 ₁-58 _(T), which can be referred to as “traction lugs” or“traction profiles”, may have any suitable shape (e.g., straight shapes,curved shapes, shapes with straight parts and curved parts, etc.).

A height H of a traction projection 58 _(x) may have any suitable value.For example, in some embodiments, the height of the traction projection58 _(x) may be at least 2 inches, in some cases at least 3 inches, insome cases at least 4 inches, in some cases at least 5 inches, and insome cases even more. The height of the traction projection 58 _(x) mayhave any other suitable value in other embodiments. The tractionprojection 58 _(x) also has a longitudinal axis 75 and a firstlongitudinal end 308 ₁ and a second longitudinal end 308 ₂ that define alength L of the traction projection 58 _(x). The longitudinal axis 75 ofthe traction projection 58 _(x) extends transversally to thelongitudinal direction of the track 21, in this example in the widthwisedirection of the track 21.

In this embodiment, each of the traction projections 58 ₁-58 _(T) is anelastomeric traction projection in that it comprises elastomericmaterial 41. The elastomeric material 41 can be any polymeric materialwith suitable elasticity. More particularly, in this embodiment, theelastomeric material 41 includes rubber. Various rubber compounds may beused and, in some cases, different rubber compounds may be present indifferent areas of each of the traction projections 58 ₁-58 _(T). Inother embodiments, the elastomeric material 41 may include anotherelastomer in addition to or instead of rubber (e.g., polyurethaneelastomer).

The traction projections 58 ₁-58 _(T) may be provided on theground-engaging outer side 27 in various ways. For example, in thisembodiment, the traction projections 58 ₁-58 _(T) are provided on theground-engaging outer side 27 by being molded with the carcass 35.

The inner side 25 of the track 21 comprises an inner surface 32 of thecarcass 35 and a plurality of inner projections 34 ₁-34 _(D) thatproject from the inner surface 32 and are positioned to contact thetrack-engaging assembly 24 (e.g., at least some of the wheels 22 ₁, 22₂, 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂) to do at least one of driving(i.e., imparting motion to) the track 21 and guiding the track 21. Sinceeach of them is used to do at least one of driving the track 21 andguiding the track 21, the inner projections 34 ₁-34 _(D) can be referredto as “drive/guide projections” or “drive/guide lugs”. In some cases, adrive/guide lug 34 i may interact with a given one of the drive wheels22 ₁, 22 ₂ to drive the track 21, in which case the drive/guide lug 34_(i) is a drive lug. In other cases, a drive/guide lug 34 _(i) mayinteract with a given one of the idler wheels 26 ₁, 26 ₂, 28 ₁-28 ₂, 30₁, 30 ₂ and/or another part of the track-engaging assembly 24 to guidethe track 21 to maintain proper track alignment and prevent de-trackingwithout being used to drive the track 21, in which case the drive/guidelug 34 _(i) is a guide lug. In yet other cases, a drive/guide lug 34_(i) may both (i) interact with a given one of the drive wheels 22 ₁, 22₃ to drive the track 21 and (ii) interact with a given one of the idlerwheels 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂ and/or another part of thetrack-engaging assembly 24 to guide the track 21, in which case thedrive/guide lug 34 _(i) is both a drive lug and a guide lug.

In this embodiment, each of the drive/guide lugs 34 ₁-34 _(D) is anelastomeric drive/guide lug in that it comprises elastomeric material42. The elastomeric material 42 can be any polymeric material withsuitable elasticity. More particularly, in this embodiment, theelastomeric material 42 includes rubber. Various rubber compounds may beused and, in some cases, different rubber compounds may be present indifferent areas of each of the drive/guide lugs 34 ₁-34 _(D). In otherembodiments, the elastomeric material 42 may include another elastomerin addition to or instead of rubber (e.g., polyurethane elastomer).

The drive/guide lugs 34 ₁-34 _(D) may be provided on the inner side 25in various ways. For example, in this embodiment, the drive/guide lugs34 ₁-34 _(D) are provided on the inner side 25 by being molded with thecarcass 35.

In this embodiment, the carcass 35 has a thickness T_(c) which isrelatively small. The thickness T_(c) of the carcass 35 is measured fromthe inner surface 32 to the ground-engaging outer surface 31 of thecarcass 35 between longitudinally-adjacent ones of the tractionprojections 58 ₁-58 _(T). For example, in some embodiments, thethickness T_(c) of the carcass 35 may be no more than 0.25 inches, insome cases no more than 0.22 inches, in some cases no more than 0.20inches, and in some cases even less (e.g., no more than 0.18 or 0.16inches). The thickness T_(c) of the carcass 35 may have any othersuitable value in other embodiments.

Elastomeric material of a given portion of the endless track 21,including the elastomeric material 38 of the carcass 35, the elastomericmaterial 41 of one of the traction projection 58 ₁-58 _(T), and theelastomeric material 42 of one of the drive/guide lugs 34 ₁-34 _(D), hasvarious material properties, including a hardness (e.g., durometers in aShore A hardness scale) and a modulus of elasticity, which can have anysuitable value.

If the elastomeric material of the given portion of the track 21 isconstituted of a single elastomer, the hardness of the elastomericmaterial of the given portion of the track 21 is the hardness of thissingle elastomer. Alternatively, if the elastomeric material of thegiven portion of the track 21 is constituted of two or more differentelastomers, the hardness of the elastomeric material of the givenportion of the track 21 is taken as an average hardness, which isobtained by multiplying a proportion of each elastomer in theelastomeric material of the given portion of the track 21 by thatelastomer's hardness and then summing the results. That is, if theelastomeric material of the given portion of the track 21 is constitutedof N elastomers, the average hardness is

$A_{avg} = {\sum\limits_{i = 1}^{N}\; {P_{i}A_{i}}}$

where A_(i) is the hardness of elastomer “i” and P_(i) is the proportion(%) of elastomer “i” in the elastomeric material of the given portion ofthe track 21. In situations where this calculated value is not aninteger and the hardness scale is only in integers, this calculatedvalue rounded to the nearest integer gives the average hardness. Anelastomer's hardness can be obtained from a standard ASTM D-2240 test(or equivalent test).

Similarly, if the elastomeric material of the given portion of the track21 is constituted of a single elastomer, the modulus of elasticity ofthe elastomeric material of the given portion of the track 21 is themodulus of elasticity of this single elastomer. Alternatively, if theelastomeric material of the given portion of the track 21 is constitutedof two or more different elastomers, the modulus of elasticity of theelastomeric material of the given portion of the track 21 is taken as anaverage modulus of elasticity, which is obtained by multiplying aproportion (%) of each elastomer in the elastomeric material of thegiven portion of the track 21 by that elastomer's modulus of elasticityand then summing the results. That is, if the elastomeric material ofthe given portion of the track 21 is constituted of N elastomers, theaverage modulus of elasticity is

$\lambda_{avg} = {\sum\limits_{i = 1}^{N}\; {P_{i}\lambda_{i}}}$

where λ_(i) is the modulus of elasticity of elastomer “i” and P_(i) isthe proportion (%) of elastomer “i” in the elastomeric material of thegiven portion of the track 21. For instance, in an embodiment in whichthe elastomeric material of the given portion of the track 21 isconstituted of two types of rubbers, say rubber “A” having a modulus ofelasticity of 1.9 MPa and being present in a proportion of 15% andrubber “B” having a modulus of elasticity of 6.3 MPa and being presentin a proportion of 85%, the average modulus of elasticity of theelastomeric material of the given portion of the track 21 is 5.64 MPa.An elastomer's modulus of elasticity can be obtained from a standardASTM D-412-A test (or equivalent test) based on a measurement at 100%elongation of the elastomer.

The track-engaging assembly 24 is configured to drive and guide thetrack 21 around the track-engaging assembly 24.

Each of the drive wheels 22 ₁, 22 ₂ is rotatable by an axle for drivingthe track 21. That is, power generated by the prime mover 15 anddelivered over the powertrain 12 of the snowmobile 10 rotates the axle,which rotates the drive wheels 22 ₁, 22 ₂, which impart motion of thetrack 21. In this embodiment, each drive wheel 22 _(i) comprises a drivesprocket engaging some of the drive/guide lugs 34 ₁-34 _(D) of the innerside 25 of the track 21 in order to drive the track 21. In otherembodiments, the drive wheel 22 _(i) may be configured in various otherways. For example, in embodiments where the track 21 comprises driveholes, the drive wheel 22 _(i) may have teeth that enter these holes inorder to drive the track 21. As yet another example, in someembodiments, the drive wheel 22 _(i) may frictionally engage the innerside 25 of the track 21 in order to frictionally drive the track 21. Thedrive wheels 22 ₁, 22 ₂ may be arranged in other configurations and/orthe track system 14 may comprise more or less drive wheels (e.g., asingle drive wheel, more than two drive wheels, etc.) in otherembodiments.

The idler wheels 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂ are not driven bypower supplied by the prime mover 15, but are rather used to do at leastone of guiding the track 21 as it is driven by the drive wheels 22 ₁, 22₂, tensioning the track 21, and supporting part of the weight of thesnowmobile 10 on the ground via the track 21. More particularly, in thisembodiment, the rear idler wheels 26 ₁, 26 ₂ are trailing idler wheelsthat maintain the track 21 in tension, guide the track 21 as it wrapsaround them, and can help to support part of the weight of thesnowmobile 10 on the ground via the track 21. The lower roller wheels 28₁-28 ₆ roll on the inner side 25 of the track 21 along the bottom run 66of the track 21 to apply the bottom run 66 on the ground. The upperroller wheels 30 ₁, 30 ₂ roll on the inner side 25 of the track 21 alongthe top run 65 of the track 21 to support and guide the top run 65 asthe track 21 moves. The idler wheels 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂may be arranged in other configurations and/or the track assembly 14 maycomprise more or less idler wheels in other embodiments.

The frame 23 of the track system 14 supports various components of thetrack-engaging assembly 24, including, in this embodiment, the idlerwheels 26 ₁, 26 ₂, 28 ₁-28 ₆, 30 ₁, 30 ₂. More particularly, in thisembodiment, the frame 23 comprises an elongate support 62 extending inthe longitudinal direction of the track system 14 along the bottom run66 of the track 21 and frame members 49 ₁-49 _(F) extending upwardlyfrom the elongate support 62.

The elongate support 62 comprises rails 44 ₁, 44 ₂ extending in thelongitudinal direction of the track system 14 along the bottom run 66 ofthe track 21. In this example, the idler wheels 26 ₁, 26 ₂, 28 ₁-28 ₆are mounted to the rails 44 ₁, 44 ₂. In this embodiment, the elongatesupport 62 comprises sliding surfaces 77 ₁, 77 ₂ for sliding on theinner side 25 of the track 21 along the bottom run 66 of the track 21.Thus, in this embodiment, the idler wheels 26 ₁, 26 ₂, 28 ₁-28 ₆ and thesliding surfaces 77 ₁, 77 ₂ of the elongate support 62 can contact thebottom run 66 of the track 21 to guide the track 21 and apply it ontothe ground for traction. In this example, the sliding surfaces 77 ₁, 77₂ can slide against the inner surface 32 of the carcass 35 and cancontact respective ones of the drive/guide lugs 34 ₁-34 _(D) to guidethe track 21 in motion. Also, in this example, the sliding surfaces 77₁, 77 ₂ are curved upwardly in a front region of the track system 14 toguide the track 21 towards the drive wheels 22 ₁, 22 ₂. In some cases,as shown in FIG. 17, the track 21 may comprise slide members 39 ₁-39_(S) that slide against the sliding surfaces 77 ₁, 77 ₂ to reducefriction. The slide members 39 ₁-39 _(S), which can sometimes bereferred to as “clips”, may be mounted via holes (i.e., windows) 40 ₁-40_(H) of the track 21. In other cases, the track 21 may be free of suchslide members.

In this embodiment, the elongate support 62 comprises sliders 33 ₁, 33 ₂mounted to respective ones of the rails 44 ₁, 44 ₂ and comprisingrespective ones of the sliding surfaces 77 ₁, 77 ₂. In this embodiment,the sliders 33 ₁, 33 ₂ are mechanically interlocked with the rails 44 ₁,44 ₂. In other embodiments, instead of or in addition to beingmechanically interlocked with the rails 44 ₁, 44 ₂, the sliders 33 ₁, 33₂ may be fastened to the rails 44 ₁, 44 ₂. For example, in someembodiments, the sliders 33 ₁, 33 ₂ may be fastened to the rails 44 ₁,44 ₂ by one or more mechanical fasteners (e.g., bolts, screws, etc.), byan adhesive, and/or by any other suitable fastener.

In some examples, each slider 33 _(i) may comprise a low-frictionmaterial which may reduce friction between its sliding surface 77 _(i)and the inner side 25 of the track 21. For instance, the slider 33 _(i)may comprise a polymeric material having a low coefficient of frictionwith the rubber of the track 21. For example, in some embodiments, theslider 33 _(i) may comprise a thermoplastic material (e.g., a Hifax®polypropylene). The slider 33 _(i) may comprise any other suitablematerial in other embodiments. For instance, in some embodiments, thesliding surface 77 _(i) of the slider 33 _(i) may comprise a coating(e.g., a polytetrafluoroethylene (PTFE) coating) that reduces frictionbetween it and the inner side 25 of the track 21, while a remainder ofthe slider 33 _(i) may comprise any suitable material (e.g., a metallicmaterial, another polymeric material, etc.).

While in embodiments considered above the sliding surface 77 _(i) ispart of the slider 33 _(i) which is separate from and mounted to eachrail 44 _(i), in other embodiments, the sliding surface 77 _(i) may bepart of the rail 44 _(i). That is, the sliding surface 77 _(i) may beintegrally formed (e.g., molded, cast, or machined) as part of the rail44 _(i).

The frame members 49 ₁-49 _(F) extend upwardly from the elongate support62 to hold the upper roller wheels 30 ₁, 30 ₂ such that the upper rollerwheels 30 ₁, 30 ₂ roll on the inner side 25 of the track 21 along thetop run 65 of the track 21.

The track-engaging assembly 24 may be implemented in any other suitableway in other embodiments.

The track system 14, including the track 21, may have various featuresto enhance its traction, floatation, and/or other aspects of itsperformance, including, for example, a lightweight design, enhancedtractive effects, an enhanced heat management capability, an enhancedresistance to lateral skidding (e.g., on a side hill), an adaptivecapability to adapt itself to different conditions (e.g., groundconditions, such as different types of snow, soil, etc.; and/or otherconditions), an adjustability of its contact patch 59, and/or otherfeatures. This may be achieved in various ways in various embodiments,examples of which will now be discussed.

1. Lightweight Track

In some embodiments, the track 21 may be designed to reduce a weight ofthe track 21 while maintaining performance of the track 21. This mayhelp to reduce power consumption, improve riding of the snowmobile 10,and/or enhance other aspects of performance of the snowmobile 10.

1.1 Thin Carcass

In some embodiments, as shown in FIG. 7, the carcass 35 may be very thinyet remain sufficiently rigid for proper traction and floatation.

For example, in some embodiments, the thickness T_(c) of the carcass 35may be no more than 0.20 inches, in some cases no more than 0.18 inches,in some cases no more than 0.16 inches, and in some cases even less(e.g., no more than 0.14 inches). For instance, in some examples ofimplementation, the thickness T_(c) of the carcass 35 may be 0.165inches or less.

Meanwhile, in such embodiments, rigidity characteristics of the carcass35 allow proper performance of the track 21. For instance, the rigiditycharacteristics of the carcass 35 may relate to (1) a longitudinalrigidity of the carcass 35, i.e., a rigidity of the carcass 35 in thelongitudinal direction of the track 21 which refers to the carcass'sresistance to bending about an axis parallel to the widthwise directionof the track 21, and/or (2) a widthwise rigidity of the carcass 35,i.e., a rigidity of the carcass 35 in the widthwise direction of thetrack 21 which refers to the carcass's resistance to bending about anaxis parallel to the longitudinal direction of the track 21.

To observe the longitudinal rigidity and the widthwise rigidity of thecarcass 35 without influence from a remainder of the track 21, as shownin FIG. 9, the carcass 35 can be isolated from the remainder of thetrack 21 (e.g., by scraping, cutting, or otherwise removing the tractionprojections 58 ₁-58 _(T) and the drive/guide lugs 34 ₁-34 _(D), or byproducing the carcass 35 without the traction projections 58 ₁-58 _(T),the carcass 35, the drive/guide lugs 34 ₁-34 _(D)) and a three-pointbending test can be performed on a sample of the carcass 35 to subjectthe carcass 35 to loading tending to bend the carcass 35 in specifiedways (i.e., bend the carcass 35 longitudinally to observe thelongitudinal rigidity of the carcass 35 and bend the carcass 35laterally to observe the widthwise rigidity of the carcass 35) andmeasure parameters indicative of the longitudinal rigidity and thewidthwise rigidity of the carcass 35. For instance in some embodiments,the three-point bending test may be based on conditions defined in astandard test (e.g., ISO 178(2010) but using elastomeric material). Forexample:

-   -   To observe the longitudinal rigidity of the carcass 35, the        three-point bending test may be performed to subject the carcass        35 to loading tending to longitudinally bend the carcass 35        until a predetermined deflection of the carcass 35 is reached        and measure a bending load at that predetermined deflection of        the carcass 35. The predetermined deflection of the carcass 35        may be selected such as to correspond to a predetermined strain        of the carcass 35 at a specified point of the carcass 35 (e.g.,        a point of the inner surface 32 of the carcass 35). For        instance, in some embodiments, the predetermined strain of the        carcass 35 may between 3% and 5%. The bending load at the        predetermined deflection of the carcass 35 may be used to        calculate a bending stress at the specified point of the carcass        35. The bending stress at the specified point of the carcass 35        may be calculated as σ=My/I, where M is the moment about a        longitudinal-bending neutral axis 63 of the carcass 35 caused by        the bending load, y is the perpendicular distance from the        specified point of the carcass 35 to the neutral axis of the        carcass 35, and I is the second moment of area about the neutral        axis of the carcass 35. The longitudinal rigidity of the carcass        35 can be taken as the bending stress at the predetermined        strain (i.e., at the predetermined deflection) of the carcass        35. Alternatively, the longitudinal rigidity of the carcass 35        may be taken as the bending load at the predetermined deflection        of the carcass 35;    -   To observe the widthwise rigidity of the carcass 35, the        three-point bending test may be performed to subject the carcass        35 to loading tending to laterally bend the carcass 35 until a        predetermined deflection of the carcass 35 is reached and        measure a bending load at that predetermined deflection of the        carcass 35. The predetermined deflection of the carcass 35 may        be selected such as to correspond to a predetermined strain of        the carcass 35 at a specified point of the carcass 35 (e.g., a        point of the inner surface 32 of the carcass 35). For instance,        in some embodiments, the predetermined strain of the carcass 35        may between 3% and 5%. The bending load at the predetermined        deflection of the carcass 35 may be used to calculate a bending        stress at the specified point of the carcass 35. The bending        stress at the specified point of the carcass 35 may be        calculated as σ=My/I, where M is the moment about a        lateral-bending neutral axis 57 of the carcass 35 caused by the        bending load, y is the perpendicular distance from the specified        point of the carcass 35 to the neutral axis of the carcass 35,        and I is the second moment of area about the neutral axis of the        carcass 35. The widthwise rigidity of the carcass 35 can be        taken as the bending stress at the predetermined strain (i.e.,        at the predetermined deflection) of the carcass 35.        Alternatively, the widthwise rigidity of the carcass 35 may be        taken as the bending load at the predetermined deflection of the        carcass 35.

Thus, in such embodiments where the carcass 35 is very thin, thewidthwise rigidity of the carcass 35 may be significantly greater thanthe longitudinal rigidity of the carcass 35. For instance, a ratio ofthe widthwise rigidity of the carcass 35 over the longitudinal rigidityof the carcass 35 may be at least 1.5, in some cases at least 2, in somecases at least 2.5, in some cases at least 3, and in some cases evenmore (e.g., 4, 5, etc.).

As another example, in some embodiments, the carcass 35 being very thinwhile sufficiently rigid may be such that a ratio of the longitudinalrigidity of the carcass 35 over the thickness T_(c) of the carcass 35 isrelatively high and/or a ratio of the widthwise rigidity of the carcass35 over the thickness T_(c) of the carcass 35 is relatively high.

The carcass 35 may be maintained sufficiently rigid in any suitable wayin various embodiments. Examples of this are discussed below.

1.1.1 Stiffer Reinforcement

In some embodiments, as shown in FIG. 8A, a reinforcement 45 _(x)embedded in the rubber 38 of the carcass 35 may be stiffer. That is, abending stiffness of the reinforcement 45 _(x) in the longitudinaldirection of the track 21 and/or a bending stiffness of thereinforcement 45 _(x) in the widthwise direction of the track 21 may berelatively high. As shown in FIG. 8A, the reinforcement 45 _(x) may be,for example, a layer of reinforcing material flexible in thelongitudinal direction of the track 21, such as a layer of reinforcingcables 37 ₁-37 _(M) or a layer of reinforcing fabric 43.

The bending stiffness of the reinforcement 45 _(x) in the longitudinaldirection of the track 21 may be measured using a three-point bendingtest performed on a sample of the reinforcement 45 _(x) to subject thereinforcement 45 _(x) to loading tending to bend the reinforcement 45_(x) in the longitudinal direction of the track 21 until a predetermineddeflection of the reinforcement 45 _(x) is reached and measure a bendingload at that predetermined deflection of the reinforcement 45 _(x), andcalculating the bending stiffness of the reinforcement 45 _(x) in thelongitudinal direction of the track 21 as a ratio of that bending loadover that predetermined deflection.

The bending stiffness of the reinforcement 45 _(x) in the longitudinaldirection of the track 21 depends on a product of an area moment ofinertia (i.e., a second moment of area) of a cross-section of thereinforcement 45 _(x) normal to the longitudinal direction of the track21 and a modulus of elasticity (i.e., Young's modulus) of a material ofthe reinforcement 45 _(x). As such, the bending stiffness of thereinforcement 45 _(x) in the longitudinal direction of the track 21 maybe increased by increasing the area moment of inertia of thecross-section of the reinforcement 45 _(x) normal to the longitudinaldirection of the track 21 and/or the modulus of elasticity of thematerial of the reinforcement 45 _(x).

Similarly, the bending stiffness of the reinforcement 45 _(x) in thewidthwise direction of the track 21 may be measured using a three-pointbending test performed on a sample of the reinforcement 45 _(x) tosubject the reinforcement 45 _(x) to loading tending to bend thereinforcement 45 _(x) in the widthwise direction of the track 21 until apredetermined deflection of the reinforcement 45 _(x) is reached andmeasure a bending load at that predetermined deflection of thereinforcement 45 _(x), and calculating the bending stiffness of thereinforcement 45 _(x) in the widthwise direction of the track 21 as aratio of that bending load over that predetermined deflection.

The bending stiffness of the reinforcement 45 _(x) in the widthwisedirection of the track 21 depends on a product of an area moment ofinertia (i.e., a second moment of area) of a cross-section of thereinforcement 45 _(x) normal to the widthwise direction of the track 21and the modulus of elasticity (i.e., Young's modulus) of the material ofthe reinforcement 45 _(x). As such, the bending stiffness of thereinforcement 45 _(x) in the widthwise direction of the track 21 may beincreased by increasing the area moment of inertia of the cross-sectionof the reinforcement 45 _(x) normal to the widthwise direction of thetrack 21 and/or the modulus of elasticity of the material of thereinforcement 45 _(x).

For example, in some embodiments, the bending stiffness of thereinforcement 45 _(x) in the longitudinal direction of the track 21 maybe at least a certain value, and/or the bending stiffness of thereinforcement 45 _(x) in the widthwise direction of the track 21 may beat least a certain value.

In some embodiments, a ratio of the bending stiffness of thereinforcement 45 _(x) in the longitudinal direction of the track 21 overthe bending stiffness of the reinforcement 45 _(x) in the widthwisedirection of the track 21 may be at least 2, in some cases at least 3,in some cases at least 4, in some cases at least 5, and in some caseseven more (e.g., 6, 7, 8 or more).

As another example, in some embodiments, the carcass 35 being very thinwhile sufficiently rigid may be such that a ratio of the bendingstiffness of the reinforcement 45 _(x) in the longitudinal direction ofthe track 21 over the thickness T_(c) of the carcass 35 is relativelyhigh and/or a ratio of the bending stiffness of the reinforcement 45_(x) in the widthwise direction of the track 21 over the thickness T_(c)of the carcass 35 is relatively high. For instance, in some embodiments,the ratio of the bending stiffness of the reinforcement 45 _(x) in thelongitudinal direction of the track 21 over the thickness T_(c) of thecarcass 35 may be at least a certain value, and/or the ratio of thebending stiffness of the reinforcement 45 _(x) in the widthwisedirection of the track 21 over the thickness T_(c) of the carcass 35 maybe at least a certain value.

As another example, in some embodiments, a ratio of the modulus ofelasticity of the reinforcement 45 _(x) in the longitudinal direction ofthe track 21 over the modulus of elasticity of the reinforcement 45 _(x)in the widthwise direction of the track 21 may be at least 2, in somecases at least 3, in some cases at least 4, in some cases at least 5,and in some cases even more (e.g., 6, 7, 8 or more). For instance, insome embodiments, the modulus of elasticity of the reinforcement 45 _(x)in the longitudinal direction of the track 21 may be at least 200 MPa,in some cases at least 300 MPa, in some cases at least 400 MPa, and insome cases even more, while the modulus of elasticity of thereinforcement 45 _(x) in the widthwise direction of the track 21 may beat least 1 GPa, in some cases at least 1.5 GPa, in some cases at least2.0 GPa, in some cases at least 2.5 GPa, and in some cases even more.Alternatively or additionally, the area moment of inertia of thecross-section of the reinforcement 45 _(x) normal to the longitudinaldirection of the track 21 and/or the area moment of inertia of thecross-section of the reinforcement 45 _(x) normal to the widthwisedirection of the track 21 may be at least a certain value. The modulusof elasticity of the reinforcement 45 _(x), the area moment of inertiaof the cross-section of the reinforcement 45 _(x) normal to thelongitudinal direction of the track 21, and/or the area moment ofinertia of the cross-section of the reinforcement 45 _(x) normal to thewidthwise direction of the track 21 may have any other suitable valuesin other embodiments.

As another example, in some embodiments, the carcass 35 being very thinwhile sufficiently rigid may be such that a ratio of the modulus ofelasticity of the reinforcement 45 _(x) over the thickness T_(c) of thecarcass 35 is relatively high, a ratio of the area moment of inertia ofthe cross-section of the reinforcement 45 _(x) normal to thelongitudinal direction of the track 21 over the thickness T_(c) of thecarcass 35 is relatively high, and/or a ratio of the area moment ofinertia of the cross-section of the reinforcement 45 _(x) normal to thewidthwise direction of the track 21 over the thickness T_(c) of thecarcass 35 is relatively high. For instance, in some embodiments, theratio of the modulus of elasticity of the reinforcement 45 _(x) in thelongitudinal direction of the track 21 over the thickness T_(c) of thecarcass 35 may be at least 1 GPa/in, in some cases at least 1.5 GPa/in,in some cases at least 2 GPa/in, and in some cases even more, and theratio of the modulus of elasticity of the reinforcement 45 _(x) in thewidthwise direction of the track 21 over the thickness T_(c) of thecarcass 35 may be at least 5 GPa/in, in some cases at least 7 GPa/in, insome cases at least 9 GPa/in, in some cases at least 12 GPa/in, and insome cases even more. Moreover, the ratio of the area moment of inertiaof the cross-section of the reinforcement 45 _(x) normal to thelongitudinal direction of the track 21 over the thickness T_(c) of thecarcass 35 may be at least a certain value, and/or the ratio of the areamoment of inertia of the cross-section of the reinforcement 45 _(x)normal to the widthwise direction of the track 21 over the thicknessT_(c) of the carcass 35 may be at least a certain value. These ratiosmay have any other suitable values in other embodiments.

1.1.2 Stiffer Elastomeric Material

In some embodiments, the elastomeric material 38 of the carcass 35 maybe stiffer. For example, in some embodiments, the 300% modulus of theelastomeric material 38 of the carcass 35 (i.e., the Young's modulus ofthe elastomeric material 38 at 300% elongation) may be at least 15 MPa,in some cases at least 20 MPa, in some cases at least 25 MPa, and insome cases even more (e.g., 30 MPa). The modulus of elasticity of theelastomeric material 38 of the carcass 35 may have any other suitablevalue in other embodiments.

1.1.3 Increased Spacing of Reinforcements

In some embodiments, respective ones of the reinforcements 45 ₁-45 _(P)embedded in the elastomeric material 38 of the carcass 35 may be spacedapart from one another significantly in order to increase thelongitudinal rigidity and/or the widthwise rigidity of the carcass 35.

For example, in some embodiments, as shown in FIG. 10, a reinforcement45 _(i) and a reinforcement 45 _(j) that mainly stiffen the track 21laterally and that are adjacent to one another in the thicknessdirection of the track 21 (i.e., there is no reinforcement mainlystiffening the track 21 laterally between the reinforcements 45 _(i), 45_(j)) may be spaced apart significantly in order to increase the track'swidthwise rigidity. Each of the reinforcements 45 _(i), 45 _(j) may thusbe spaced apart significantly from the lateral-bending neutral axis 57of the carcass 35.

For instance, in some embodiments, a ratio of a spacing S_(r-w) of thereinforcements 45 _(i), 45 _(j) in the thickness direction of the track21 over the thickness T_(c) of the carcass 35 may be at least 0.4, insome cases at least 0.5, in some cases at least 0.6, and in some caseseven more. As an example, in some embodiments, where the thickness T_(c)of the carcass 35 is 5 mm, the spacing S_(r-w) of the reinforcements 45_(i), 45 _(j) may be at least 2 mm, in some cases at least 2.5 mm, insome cases at least 3 mm, and in some cases even more. The ratio of thespacing S_(r-w) of the reinforcements 45 _(i), 45 _(j) over thethickness T_(c) of the carcass 35, the spacing S_(r-w) of thereinforcements 45 _(i), 45 _(j), and/or the thickness T_(c) of thecarcass 35 may have any other suitable value in other embodiments.

In some embodiments, a stiffness of the reinforcement 45 _(i) in thewidthwise direction of the track 21 and a stiffness of the reinforcement45 _(j) in the widthwise direction of the track 21 may be substantiallyidentical. For instance, in some cases, the reinforcements 45 _(i), 45_(j) may be of a common type or structure. For example, thereinforcements 45 _(i), 45 _(j) may be substantially identical layers ofreinforcing cables or of reinforcing fabric.

Alternatively, in some embodiments, the stiffness of the reinforcement45 _(i) in the widthwise direction of the track 21 and the stiffness ofthe reinforcement 45 _(j) in the widthwise direction of the track 21 maybe substantially different. For example, in some cases, thereinforcements 45 _(i), 45 _(j) may be layers of reinforcing cables thatdiffer from one another (e.g., in terms of cable material, diameter,pitch, etc.). As another example, in some cases, the reinforcements 45_(i), 45 _(j) may be layers of reinforcing fabric that differ from oneanother (e.g., in terms of fabric material, configuration (e.g., weft,warp, bias, etc.), etc.). As yet another example, in some cases, thereinforcements 45 _(i), 45 _(j) may be respective ones of a layer ofreinforcing cable and a layer of reinforcing fabric.

In a similar manner, in some embodiments, as shown in FIG. 11, areinforcement 45 _(m) and a reinforcement 45 _(n) that mainly stiffenthe track 21 longitudinally and that are adjacent to one another in thethickness direction of the track 21 (i.e., there is no reinforcementmainly stiffening the track 21 longitudinally between the reinforcements45 _(m), 45 _(n)) may be spaced apart significantly in order to increasethe track's longitudinal rigidity. Each of the reinforcements 45 _(m),45 _(n) may thus be spaced apart significantly from alongitudinal-bending neutral axis 63 of the carcass 35.

For instance, in some embodiments, a ratio of a spacing S_(r-l) of thereinforcements 45 _(m), 45 _(n) in the thickness direction of the track21 over the thickness T_(c) of the carcass 35 may be at least 0.4, insome cases at least 0.5, in some cases at least 0.6, and in some caseseven more. As an example, in some embodiments, where the thickness T_(c)of the carcass 35 is 5 mm, the spacing S_(r-l) of the reinforcements 45_(m), 45 _(n) may be at least 2 mm, in some cases at least 2.5 mm, insome cases at least 3 mm, and in some cases even more. The ratio of thespacing S_(r-l) of the reinforcements 45 _(m), 45 _(n) over thethickness T_(c) of the carcass 35, the spacing S_(r-l) of thereinforcements 45 _(m), 45 _(n), and/or the thickness T_(c) of thecarcass 35 may have any other suitable value in other embodiments.

In some embodiments, a stiffness of the reinforcement 45 _(m) in thelongitudinal direction of the track 21 and a stiffness of thereinforcement 45 _(n) in the longitudinal direction of the track 21 maybe substantially identical. For instance, in some cases, thereinforcements 45 _(m), 45 _(n) may be of a common type or structure.For example, the reinforcements 45 _(m), 45 _(n) may be substantiallyidentical layers of reinforcing cables or of reinforcing fabric.

Alternatively, in some embodiments, the stiffness of the reinforcement45 _(m) in the longitudinal direction of the track 21 and the stiffnessof the reinforcement 45 _(n) in the longitudinal direction of the track21 may be substantially different. For example, in some cases, thereinforcements 45 _(m), 45 _(n) may be layers of reinforcing cables thatdiffer from one another (e.g., in terms of cable material, diameter,pitch, etc.). As another example, in some cases, the reinforcements 45_(m), 45 _(n) may be layers of reinforcing fabric that differ from oneanother (e.g., in terms of fabric material, configuration (e.g., weft,warp, bias, etc.), etc.). As yet another example, in some cases, thereinforcements 45 _(m), 45 _(n) may be respective ones of a layer ofreinforcing cable and a layer of reinforcing fabric.

1.2 Low-Density Elastomeric Material

In some embodiments, as shown in FIG. 12, the elastomeric material ofthe track 21 may comprise elastomeric material 50 having a density thatis relatively low. This “lower-density” elastomeric material 50 may helpto reduce the weight of the track 21.

For example, in this embodiment, in addition to the lower-densityelastomeric material 50, the elastomeric material of the track 21comprises elastomeric material 52 having a density that is relativelyhigher such that the lower-density elastomeric material 50 is less densethan this “higher-density” elastomeric material 52. For instance, insome embodiments, a ratio of the density of the lower-densityelastomeric material 50 over the density of the higher-densityelastomeric material 52 may be no more than 0.9, in some cases no morethan 0.8, in some cases no more than 0.7, in some cases no more than0.6, and in some cases even less (e.g., no more than 0.5). This ratiomay have any other suitable value in other embodiments.

For instance, in some embodiments, the density of the lower-densityelastomeric material 50 may be no more than 1.4 g/cm³, in some cases nomore than 1.2 g/cm³, in some cases no more than 1.0 g/cm³, in some casesno more than 0.8 g/cm³ and in some cases even less, and/or the densityof the higher-density elastomeric material 52 may be at least 1.4 g/cm³,in some cases at least 1.6 g/cm³, in some cases at least 1.8, in somecases at least 2.0 g/cm³ and in some cases even more. The density of thelower-density elastomeric material 50 and/or the density of thehigher-density elastomeric material 52 may have any other suitable valuein other embodiments.

More particularly, in this embodiment, the lower-density elastomericmaterial 50 is internal elastomeric material 54 of the track 21 that islocated away from a periphery 56 of the track 21 (i.e., the inner side25, the ground-engaging outer side 27, and lateral edges 55 ₁, 55 ₂ ofthe track 21), such as elastomeric material 38 inside the carcass 35,elastomeric material 41 inside the traction projections 58 ₁-58 _(T),and/or elastomeric material 42 inside the drive/guide lugs 34 ₁-34 _(D),while the higher-density elastomeric material 52 is peripheralelastomeric material 60 forming at least part of the periphery 56 of thetrack 21, such as elastomeric material 62 of the inner side 25 of thetrack 21, elastomeric material 64 of the ground-engaging outer side 27of the track 21, and/or elastomeric material 68 of the lateral edges 55₁, 55 ₂ of the track 21. This may help to reduce the weight of the track21 while providing suitable wear resistance and/or other usefulproperties in external regions of the track 21 that may be expected towear faster and/or be subject to other particular effects during use.

In this embodiment, the elastomeric material 62 of the inner side 25 ofthe track 21 comprises an elastomeric material of the inner surface 32of the carcass 35 and an elastomeric material of an outer surface of thedrive/guide lugs 34 ₁-34 _(D); the elastomeric material 64 of theground-engaging outer side 27 of the track 21 comprises an elastomericmaterial of the ground-engaging outer surface 31 of the carcass 35 andan elastomeric material 41 of an outer surface of the tractionprojections 58 ₁-58 _(T); and the elastomeric material 38 inside thecarcass 35 is part of the internal elastomeric material 54 spaced fromthe inner surface 32 and the ground-engaging outer surface 31 of thecarcass 35. In this example, the internal elastomeric material 54 isthus encapsulated in the elastomeric material 62, 64, 68 of the innerside 25, the ground-engaging outer side 27 and the lateral edges 55 ₁,55 ₂ of the track 21.

In this embodiment, a quantity of the internal elastomeric material 54is significant to allow this elastomeric material to occupy more spacewithin the track 21. For example, in some embodiments, as shown in FIGS.13A, 13B and 14, a thickness T_(q) of the internal elastomeric material54 inside the carcass 35 may occupy at least 20% of the thickness T_(c)of the carcass 35, in some cases at least 30% of the thickness T_(c) ofthe carcass 35, in some cases at least 40% of the thickness T_(c) of thecarcass 35, in some cases at least 50% of the thickness T_(c) of thecarcass 35, and in some cases even more (e.g., 60%, 70% or more). Inthis example of implementation, the thickness T_(q) of the internalelastomeric material 54 inside the carcass 35 occupies at least amajority, in this case at least three-quarters, of the thickness T_(c)of the carcass 35. The thickness T_(q) of the internal elastomericmaterial 54 inside the carcass 35 may have any other suitable value inother embodiments. As another example, in some embodiments, a widthW_(q) of the internal elastomeric material 54 inside the carcass 35 mayoccupy at least 20% of a width W of the track 21 (measured between thelateral edges 55 ₁, 55 ₂ of the track 21), in some cases at least 30% ofthe width W of the track 21, in some cases at least 40% of the width Wof the track 22, in some cases at least 50% of the width W of the track21, and in some cases even more (e.g., 60%, 70% or more). In thisexample of implementation, the width W_(q) of the internal elastomericmaterial 54 inside the carcass 35 occupies at least a majority, in thiscase at least three-quarters, of the width W of the track 21. In thisexample, the internal elastomeric material 54 inside the carcass 35 isconstituted of a single segment. In other embodiments, the internalelastomeric material 54 inside the carcass 35 may be constituted ofseparate segments (e.g., two segments) such that its width W_(q)corresponds to a sum of a width of each of these separate segments. Thewidth W_(q) of the internal elastomeric material 54 inside the carcass35 may have any other suitable value in other embodiments. As yetanother example, in some embodiments, a weight of the internalelastomeric material 54 inside the carcass 35 may constitute at least25% of a total weight of elastomeric material of the track 21, in somecases at least 30% of the total weight of elastomeric material of thetrack 21, in some cases at least 35% of the total weight of elastomericmaterial of the track 21, in some cases at least 40% of the total weightof elastomeric material of the track 21, and in some cases even more.

This arrangement of the internal elastomeric material 54 inside thecarcass 35 and the elastomeric material 62, 64, 68 of the inner side 25,the ground-engaging outer side 27 and the lateral edges 55 ₁, 55 ₂ ofthe track 21 may be achieved by placing elastomeric components (e.g.,sheets or other layers of elastomeric material and/or blocks ofelastomeric material previously produced using any suitable process suchas calendering, molding, etc.) in a mold and consolidating them.Different elastomeric compounds may be used in the inner side 25, theground-engaging outer side 27 and/or the lateral edges 55 ₁, 55 ₂ of thetrack 21 than inside the carcass 35 (e.g., rubber compounds havingdifferent base polymers, different concentrations and/or types of carbonblack, and/or different contents of sulfur or other vulcanizing agent).

The lower-density elastomeric material 50 may be implemented in anysuitable way in various embodiments.

For example, in some embodiments, the lower-density elastomeric material50 may be cellular elastomeric material (e.g., cellular rubber, a.k.afoam rubber or expanded rubber). The cellular elastomeric material 50 iselastomeric material which contains cells (e.g., bubbles) created by afoaming agent (e.g., a gas (e.g., air) or a gas-producing agent (e.g.,sodium bicarbonate)) during manufacturing of the cellular elastomericmaterial 50. The cells of the cellular elastomeric material 50 mayinclude closed cells and/or open cells.

For instance, the cellular elastomeric material 50 may be expandedrubber (a.k.a. foam rubber).

The cellular elastomeric material 50 may be manufactured in any suitableway. For instance, a foaming agent may be sprayed, poured or molded withan elastomeric material (e.g., rubber) to react with the elastomericmaterial in order to produce the cellular elastomeric material 50. Thefoaming agent may be azodicarbonamide (ADC), sulfonylhydrazides (OBSH,TSH and/or BSH), silica, a suitable ceramic material or any othersuitable foaming agent.

The cellular elastomeric material 50 may be molded with thehigher-density elastomeric material 52 in any suitable way. Forinstance, the cellular elastomeric material 50 may be molded in a firstmold and then inserted into a second mold where it is overmolded by thehigher-density elastomeric material 52.

In other embodiments, the cellular elastomeric material 50 may be moldedtogether with the higher-density elastomeric material 52 via compressionmolding.

In this embodiment, the higher-density elastomeric material 52 is notcellular elastomeric material, i.e., it substantially does not containcells created by a foaming agent during its manufacturing.

In other embodiments, both the lower-density elastomeric material 50 andthe higher-density elastomeric material 52 may be cellular.

The lower-density elastomeric material 50 may constitute other parts ofthe track 21 and/or may otherwise be provided in different ways in thetrack 21 in other embodiments.

For example, in some embodiments, as shown in FIG. 15, in addition tothe lower-density elastomeric material 50, the track 21 may comprise aplurality of higher-density elastomeric materials 70 ₁, 70 ₂ that havedifferent densities and that are denser than the lower-densityelastomeric material 50. For instance, the higher-density elastomericmaterial 70 ₁ may be denser than the higher-density elastomeric material70 ₂ such that the lower-density elastomeric material 50 and thehigher-density elastomeric material 70 ₁ have a lowest and a highestdensity respectively while the higher-density elastomeric material 70 ₂has a medium density. The lower-density and the higher densityelastomeric materials 50, 70 ₁, 70 ₂ may be arranged in any suitableway. For example, the lower-density and the higher-density elastomericmaterials 50, 70 ₁, 70 ₂ may be arranged to form a density gradient. Forinstance, the lower-density elastomeric material 50 may be an innermostelastomeric material, the higher-density elastomeric material 70 ₁ maybe an outermost elastomeric material, and the higher-density elastomericmaterial 70 ₁ may be a middle elastomeric material.

In some embodiments, as shown in FIG. 16, the lower-density elastomericmaterial 50 may form part of the periphery 56 of the track 21. Forinstance, in some cases, the lower-density elastomeric material 50 mayform part of the periphery 56 at the inner side 25 of the track 21 sincethe inner side 25 of the track 21 is less exposed to wear than the outerside 27 of the track 21. In some embodiments, the lower-densityelastomeric material 50 may form part of the periphery 56 of the track21 at the outer side 27 of the track 21.

The lower-density elastomeric material 50 may constitute at least a bulkof the elastomeric material of the track 21. For instance, thelower-density elastomeric material 50 may constitute at least a majorityof the elastomeric material of the track 21. In some embodiments, thelower-density elastomeric material 50 may constitute an entirety of theelastomeric material of the track 21 (e.g., there is no higher-densityelastomeric material).

In some embodiments, the lower-density elastomeric material 50 maycomprise other types of material rather than cellular elastomericmaterial. For instance, the lower-density elastomeric material 50 maycomprise any suitable low-density polymeric material. For example, thelower-density elastomeric material 50 may comprise polypropylene,polyethylene or any other suitable material.

1.3 Track with Few or No Slide Members (e.g., “Clips”)

In some embodiments, as shown in FIG. 18, the track 21 may have fewer orno slide member (e.g., “clips”) such as the slide members 39 ₁-39 _(S)to slide against the sliding surfaces 77 ₁, 77 ₂ of the rails 44 ₁, 44 ₂of the track-engaging assembly 24.

For instance, in some embodiments, the track 21 may comprise the slidemembers 39 ₁-39 _(S) in a reduced number. In such embodiments,longitudinally-adjacent ones of the slide members 39 ₁-39 _(S) may besignificantly spaced apart from one another. More specifically, as shownin FIG. 19, a longitudinal spacing J defined betweenlongitudinally-adjacent ones of the slide members 39 ₁-39 _(S) may belarge. For example, in some cases the longitudinal spacing J may be atleast one-fifth of the length of the track 21, in some cases at leastone-quarter of the length of the track 21, in some cases at leastone-third of the length of the track 21, in some cases at least half ofthe length of the track 21, and in some cases even more.

In some embodiments, the longitudinal spacing J defined betweenlongitudinally-adjacent ones of the slide members 39 ₁-39 _(S) may besuch that no more than a certain number of slide members 39 ₁-39 _(S)can contact a rail 44 _(i) at any given instant. For example, in somecases, no more than three slide members 39 ₁-39 _(S) may contact therail 44 _(i) at any given instant, in some cases no more than two slidemembers 39 ₁-39 _(S) may contact the rail 44 _(i) at any given instant,and in some cases no more than one slide member 39 ₁-39 _(S) may contactthe rail 44 _(i) at any given instant.

In other embodiments, the track 21 may be free of slide members and thusmay be referred to as a “clipless” track.

2. Different Traction Projections with Different Tractive Effects

In some embodiments, as shown in FIG. 20, respective ones of thetraction projections 58 ₁-58 _(T) may have different characteristics(e.g., different shapes and/or different rigidity characteristics) togenerate different tractive effects on the ground. For instance, thismay allow the track 21 to perform well in different ground conditions,such as different types of snow, soil, etc.

For example, in this embodiment, longitudinally-successive tractionprojections 58 _(i)-58 _(k) that succeed one another in the longitudinaldirection of the track 21 differ in height. In this example, the heightof the traction projection 58 _(i) (i.e., H₁) is greater than the heightof the traction projections 58 _(j) (i.e., H₂), which is greater thanthe height of the traction projection 58 _(k) (i.e., H₃). This patternmay be repeated over other longitudinally-successive ones of thetraction projections 58 ₁-58 _(T). For instance, this may allow thetraction projections 58 ₁-58 _(T) to have different degrees ofengagement with the ground in different ground conditions.

In this embodiment, the longitudinally-successive traction projections58 _(i)-58 _(k) may have different rigidity characteristics.

For instance, a taller one of the longitudinally-successive tractionprojections 58 _(i)-58 _(k) (e.g., 58 _(i)) may comprise an upperportion 72 that is more flexible than an upper portion 74 of a lower oneof the longitudinally-successive traction projections 58 _(i)-58 _(k)(e.g., 58 _(i)). For example, a modulus of elasticity of a material 76of the upper portion 72 of the traction projection 58 _(i) may be lowerthan a modulus of elasticity of a material 78 of the upper portion 74 ofthe traction projection 58 _(i).

For instance, in some embodiments, a ratio of the modulus of elasticityof the material 76 of the upper portion 72 of the traction projection 58_(i) over the modulus of elasticity of the material 78 of the upperportion 74 of the traction projection 58 _(i) may be at least 1.5, insome cases at least 2, in some cases at least 2.5, in some cases atleast 3, and in some cases even more.

3. Traction Projections Providing Enhanced Heat Management

In some embodiments, as shown in FIGS. 21 and 22, respective ones of thetraction projections 58 ₁-58 _(T) may be configured to allow the track21 to better manage heat generated within its elastomeric material as itmoves around the track-engaging assembly 24. Notably, this may reduceheat buildup within the track 21 by allowing more heat to be transferredto the track's environment.

For example, in some embodiments, a traction projection 58 _(x) may bedesigned such that a base 80 of the traction projection 58 _(x) fromwhich it projects from the carcass 35 leaves more of the ground-engagingouter surface 31 of the carcass 35 exposed to facilitate transfer ofheat from the carcass 35 to the track's environment. This may thusreduce heat buildup within the carcass 35.

In this embodiment, the traction projection 58 _(x) comprises a recessedspace 82 that defines a recessed area 84 at the base 80 of the tractionprojection 58 _(x) which leaves an open area 86 of the ground-engagingouter surface 31 of the carcass 35 exposed. The recessed area 84 at thebase 80 of the traction projection 58 _(x) is delimited by an imaginaryboundary 88 made up of the base 80 of the traction projection 58 _(x)and straight lines circumscribing the base 80 of the traction projection58 _(x).

The recessed area 84 at the base 80 of the traction projection 58 _(x)may be significant in relation to a cross-sectional area of the base 80of the traction projection 58 _(x). For example, in some embodiments, aratio of the recessed area 84 at the base 80 of the traction projection58 _(x) over the cross-sectional area of the base 80 of the tractionprojection 58 _(x) may be at least 30%, in some cases at least 40%, insome cases at least 50%, in some cases at least 60%, in some cases atleast 70%, in some cases at least 80%, and in some cases even more. Thisratio may have any other suitable value in other embodiments.

In this embodiment, the traction projection 58 _(x) comprises narrowportions 90 and enlarged portions 92 that are larger than the narrowportions 90 in the longitudinal direction of the track 21. For instance,the narrow portions 90 may be walls forming “paddles” and the enlargedportions 92 may be blocks forming “columns”.

In some embodiments, a ratio of a dimension of a narrow portion 90 overa dimension of an enlarged portion 92 in the longitudinal direction ofthe track 21 may be at least 0.05, in some cases at least 0.1, in somecases at least 0.15, in some cases at least 0.2 and in some cases evenmore (e.g., 0.25, 0.3, etc.). Moreover, in some embodiments, a ratio ofa dimension of a narrow portion 90 over a dimension of an enlargedportion 92 in the widthwise direction of the track 21 may be at least 1,in some cases at least 1.5, in some cases at least 2, in some cases atleast 2.5 and in some cases even more (e.g., 3).

The recessed space 82 and the recessed area 84 at the base 80 of thetraction projection 58 _(x) may be configured in any other suitable wayin other embodiments.

4. Enhancement Based on Spacing of Traction Projections

In some embodiments, as shown in FIG. 5, a longitudinal spacing S_(t) ofadjacent traction projections 58 _(i), 58 _(j) (i.e., a spacing of theadjacent traction projections 58 _(i), 58 _(j) in the longitudinaldirection of the track 21), which can be referred to as a “pitch” of theadjacent traction projections 58 _(i), 58 _(j), may be used to improve aperformance of the track 21.

For example, in some embodiments, as shown in FIG. 23, the pitch S_(t)of the adjacent traction projections 58 _(i), 58 _(j) may be greaterthan a longitudinal spacing S_(i) of adjacent drive/guide lugs 34 _(i),34 _(j) (i.e., a spacing of the adjacent drive/guide lugs 34 _(i), 34_(j) in the longitudinal direction of the track 21), which can bereferred to as a “pitch” of the adjacent drive/guide lugs 34 _(i), 34_(j). For instance, in some embodiments, a ratio of the pitch S_(t) ofthe adjacent traction projections 58 _(i), 58 _(j) over the pitch S_(i)of the adjacent drive/guide lugs 34 _(i), 34 _(j) may be at least 1.2,in some cases at least 1.5, in some cases at least 2, in some cases atleast 3, and in some cases even more. This ration may have any othersuitable value in other embodiments.

In some examples of implementation, the pitch S_(t) of the adjacenttraction projections 58 _(i), 58 _(j) may be such that at least two ofthe holes (i.e., windows) 40 ₁-40 _(H) of the track 21 that succeed oneanother in the longitudinal direction of the track 21 are disposedbetween the adjacent traction projections 58 _(i), 58 _(j).

Moreover, in some examples of implementation, the pitch S_(t) of theadjacent traction projections 58 _(i), 58 _(j) may be such that at leasttwo of the reinforcements 45 _(x) of the track 21 that succeed oneanother in the longitudinal direction of the track 21 are disposedbetween the traction projections 58 _(i), 58 _(j).

In some embodiments, as shown in FIG. 24, the pitch S_(t) of adjacentones of the traction projections 58 ₁-58 _(T) may vary in thelongitudinal direction of the track 21 such that the pitch S_(t) of theadjacent traction projections 58 _(i), 58 _(j) is different from thepitch S_(t) of adjacent traction projections 58 _(m), 58 _(n).

For instance, in some embodiments, a ratio of the pitch S_(t) of theadjacent traction projections 58 _(i), 58 _(j) over the pitch S_(t) ofadjacent traction projections 58 _(m), 58 _(n) may be at least 1, insome cases at least 1.5, in some cases at least 2, and in some caseseven more.

In some embodiments, certain ones of the traction projections 58 ₁-58_(T) may be misaligned with respect to one another in the widthwisedirection of the track 21. For instance, certain ones of the tractionprojections 58 ₁-58 _(T) may not overlap with one another in thewidthwise direction of the track 21. For example, certain tractionprojections 58 ₁-58 _(T) may be “side” traction projections 58 ₁-58 _(T)that are disposed substantially to a side of the track 21 in thewidthwise direction of the track 21 while other ones of the tractionprojections 58 ₁-58 _(T) may be “center” traction projections 58 ₁-58_(T) that are disposed substantially centrally of the track 21 in thewidthwise direction of the track 21. A pitch of the side tractionprojections may be different from a pitch of the center tractionprojections. For example, a ratio of the pith of the side tractionprojections over the pitch of the center traction projections may be nomore than 0.9, in some cases no more than 0.8, in some cases no morethan 0.7, and in some cases even less. This ratio may have any suitablevalue in other embodiments.

5. Enhanced Resistance to Lateral Skidding

In some embodiments, as shown in FIGS. 25 and 26, the ground-engagingouter side 27 of the track 21 may be configured to oppose a tendency ofthe track 21 to skid sideways (i.e., laterally) when the snowmobile 10is travelling in a given direction, such as, for example, when thesnowmobile 10 is travelling on (e.g., crossing) a slope terrain 94 likea side hill or other inclined ground area.

For example, in some embodiments, the ground-engaging outer side 27 ofthe track 21 may comprise lateral stabilizers 96 ₁-96 _(n) projectingfrom the ground-engaging outer surface 31 to oppose a tendency of thetrack 21 to skid transversely to a direction of motion of the snowmobile10. In this embodiment, each of the lateral stabilizers 96 ₁-96 _(n)comprises elastomeric material 98. The lateral stabilizers 96 ₁-96 _(n)can be provided and connected to the carcass 35 in the mold during thetrack's molding process.

Where the snowmobile 10 travels such that there is a tendency of thetrack 21 to skid sideways to the snowmobile's direction of motion, suchas on the slope terrain 94, the lateral stabilizers 96 ₁-96 _(n)generate lateral forces that oppose the tendency of the track 21 to skidsideways. This may facilitate keeping the snowmobile 10 in its directionof motion on the slope terrain 94.

In this embodiment, the lateral stabilizers 96 ₁-96 _(n) are locatedadjacent to the lateral edges 55 ₁, 55 ₂ of the track 21. In thisexample, the lateral stabilizers 96 ₁-96 _(n) are located atlongitudinal ends of respective ones of the traction projections 58 ₁-58_(T).

In this embodiment, as shown in FIG. 27, each lateral stabilizer 96 _(i)is elongated transversally to the widthwise direction of the track 21.More particularly, the lateral stabilizer 96 _(i) has a longitudinalaxis 67 that is transversal to the widthwise direction of the track 21and defines its length L_(S), a width W_(L) normal to its longitudinalaxis 67, and a height H_(S) in the thickness direction of the track 21.In this example, the longitudinal axis 67 of the lateral stabilizer 96_(i) is substantially normal to the widthwise direction of the track 21,i.e., substantially parallel to the longitudinal direction of the track21.

In this embodiment, the lateral stabilizer 96 _(i) protrudes, in thelongitudinal direction, beyond a traction projection 58 _(x) at the endof which it is located. As such, the length L_(S) of the lateralstabilizer 96 _(i) is greater than a front-to-rear dimension L_(L) ofthe traction projection 58 _(x). For example, in some cases a ratioL_(S)/L_(L) of the length of the lateral stabilizer 96 _(i) to thefront-to-rear dimension L_(L) of the traction projection 58 _(x) may beat least 1.2, in some cases at least 1.3, in some cases at least 1.4, insome cases at least 1.5, and in some cases even more (e.g., 2 or more).

The lateral stabilizers 96 ₁-96 _(n) are arranged to occupy asignificant part of a gap G_(T) in the longitudinal direction of thetrack 21 between adjacent ones of the traction projections 58 ₁-58 _(T).For instance, in this embodiment, adjacent lateral stabilizers 96 _(i),96 _(j) occupy a significant part of the gap G_(T) between adjacenttraction projections 58 _(i), 58 _(j). For example, the lateralstabilizers 96 _(i), 96 _(j) occupy at least a majority of the gap G_(T)between the traction projections 58 _(i), 58 _(j), in some cases atleast two-thirds the gap G_(T) between the traction projections 58 _(i),58 _(j), in some cases at least three-quarters of the gap G_(T) betweenthe traction projections 58 _(i), 58 _(j), and in some cases even more(e.g., up to an entirety of the gap G_(T) between the tractionprojections 58 _(i), 58 _(j)).

In a variant, with additional reference to FIG. 28, a single lateralstabilizer 96 _(i) may occupy at least majority of the gap G_(T) betweenthe traction projections 58 _(i), 58 _(j), in some cases at leasttwo-thirds the gap G_(T) between the traction projections 58 _(i), 58_(j), in some cases at least three-quarters of the gap G_(T) between thetraction projections 61 _(i), 61 _(j), and in some cases even more(e.g., up to an entirety of the gap G_(T) between the tractionprojections 61 _(i), 61 _(j)).

In a variant, with additional reference to FIG. 29, the lateralstabilizers 96 ₁-96 _(n) may be disposed at the longitudinal ends ofselected ones of the traction projections 58 ₁-58 _(T), i.e., thelateral stabilizers 96 ₁-96 _(n) may not be disposed at the longitudinalends of each traction projection 58 _(i). For instance, the lateralstabilizers may be distributed in the longitudinal direction of thetrack 21 such that a pitch of the lateral stabilizers (i.e., a spacingbetween adjacent lateral stabilizers 96 _(i), 96 _(j) is different thanthe pitch S_(t) of the traction projections 58 ₁-58 _(T). In thisexample, the lateral stabilizers 96 ₁-96 _(n) are disposed atlongitudinal ends of every second traction projection 58 _(i) in thelongitudinal direction of the track 21. In other words, the pitch of thelateral stabilizers is twice the pitch S_(t) of the traction projections58 ₁-58 _(T). In other words, a ratio of the pitch of the lateralstabilizers 96 ₁-96 _(n) over the pitch S_(t) of the tractionprojections 58 ₁-58 _(T) may be at least 1, in some cases at least 2, insome cases at least 3, in some cases at least 4, and in some cases evenmore.

In another variant, with additional reference to FIG. 30, a lateralstabilizer 96 _(i) may be located away from the lateral edges 55 ₁, 55 ₂of the track 21. For instance, the lateral stabilizer 96 _(i) may belocated remote from the longitudinal ends of the traction projections 58₁-58 _(T). For example, the lateral stabilizer 96 _(i) may be located ina center region of the track 21 (i.e., a center region in the widthwisedirection of the track 21). More particularly, in this example, thelateral stabilizer 96 _(i) is located in a center third of the width Wof the track 21.

In another variant, with additional reference to FIG. 31, the track 21may comprise any number of lateral stabilizers 96 ₁-96 _(n) that arespaced apart in the widthwise direction of the track 21 but overlappingin the longitudinal direction of the track 21. For instance, while theembodiment of FIG. 26 shows two lateral stabilizers 96 _(i), 96 _(j)that are spaced apart in the widthwise direction of the track 21 andoverlapping in the longitudinal direction of the track 21, in thisvariant, the track 21 may comprise at least three lateral stabilizers 96₁-96 _(n) that are spaced apart in the widthwise direction of the track21 and overlapping in the longitudinal direction of the track 21. Insome cases, the track 21 may comprise more lateral stabilizers 96 ₁-96_(n) (e.g., four) that are spaced apart in the widthwise direction ofthe track 21 and overlapping in the longitudinal direction of the track21.

In yet another variant, a lateral stabilizer 96 _(i) may be locatedbetween successive ones of the traction projections 58 ₁-58 _(T) in thelongitudinal direction of the track 21. For example, as shown in FIG.32, each lateral stabilizer 96 _(i) may be located between successiveones of the traction projections 58 ₁-58 _(T) in the longitudinaldirection of the track 21 such that lateral stabilizers 96 _(i), 96 _(j)that are spaced apart in the widthwise direction of the track 21 andoverlapping in the longitudinal direction of the track 21 do not overlapwith a traction projection 58 _(i) in the longitudinal direction of thetrack 21.

In some embodiments, as shown in FIG. 33, the ground-engaging outer side27 of the track 21 may comprise uneven surfaces 102 ₁-102 _(U) thatproject from the ground-engaging outer surface 31 and have a texture 104to oppose a tendency of the track 21 to skid transversely to thedirection of motion of the snowmobile 10. The uneven surfaces 102 ₁-102_(U) of the ground-engaging outer side 27 of the track 21 may be part ofthe traction projections 58 ₁-58 _(T) and/or the lateral stabilizers 96₁-96 _(n), if present. For instance, the uneven surfaces 102 ₁-102 _(U)may be part of a lateral surface (i.e., a surface facing transversallyof the longitudinal direction of the track system 14) of the tractionprojections 58 ₁-58 _(T) and/or the lateral stabilizers 96 ₁-96 _(n).For example, the uneven surfaces 102 ₁-102 _(U) may be part of an outerlateral surface of a traction projections 58 _(i) (i.e., a lateralsurface of a traction projections 58 _(i) that is closest to a lateraledge 55 _(i) of the track 21). Moreover, in some examples, as shown inFIG. 34, the uneven surfaces 102 ₁-102 _(U) may be part of an outerlateral surface of a lateral stabilizer 96 _(i) (i.e., a lateral surfaceof a lateral stabilizer 96 _(i) that is closest to a lateral edge 55_(i) of the track 21).

The texture 104 comprises a plurality of formations 106 ₁-106 _(F) thatincrease friction to oppose a tendency of the track 21 to skidtransversely to the direction of motion of the snowmobile 10. Moreparticularly, the formations 106 ₁-106 _(F) provide an increased numberof ground-engaging faces on the lateral surfaces of the tractionprojections 58 ₁-58 _(T) and/or the lateral stabilizers 96 ₁-96 _(n)such that the traction projections 58 ₁-58 _(T) and/or the lateralstabilizers 96 ₁-96 _(n) have an increased frictional engagement withthe ground to oppose a tendency of the track 21 to skid transversely tothe direction of motion of the snowmobile 10.

The formations 106 ₁-106 _(F) may be configured in various ways invarious embodiments.

For instance, in some embodiments, as shown in FIG. 35A, the formations106 ₁-106 _(F) may be configured in a step-like manner such that theformations form steps 108 ₁-108 _(S) in an ascending manner from abottom portion to a top portion of the traction projection 58 _(i). Inother embodiments, as shown in FIGS. 35B and 35C, the formations 106₁-106 _(F) may be configured to form projections 110 ₁-110 _(P). Theprojections 110 ₁-110 _(F) may have any suitable shape. For instance,the projections 110 ₁-110 _(F) may have a rectangular shape (as shown inFIG. 35B), a rounded shape, a triangular shape (as shown in FIG. 35C) orany other suitable shape. In yet other embodiments, as shown in FIG.35D, the formations 106 ₁-106 _(F) may be configured to form recesses112 ₁-112 _(M).

The formations 106 ₁-106 _(F) may be configured differently in otherembodiments. For instance, the formations 106 ₁-106 _(F) may be spacedevenly from one another as shown in FIGS. 35A to 35D or, alternatively,the formations 106 ₁-106 _(F) may be unevenly spaced from one anothersuch that a pitch defined between successive ones of the formations 106₁-106 _(F) varies. Moreover, the formations 106 ₁-106 _(F) may extendalong only a portion of the height of the traction projection 58 _(i)and/or a height of the lateral stabilizer 96 _(i). For example, as shownin FIG. 37, the formations 106 ₁-106 _(F) may extend along a top portion107 of the traction projection 58 _(i) while a bottom portion 109 of thetraction projection 58 _(i) may not comprise any of the formations 106₁-106 _(F). The top portion 107 of the traction projection 58 _(i) maycorrespond to at least 10% of a height H of the traction projection 58_(i), in some cases at least 30%, in some cases at least 50%, in somecases at least 60%, and in some cases even more (e.g., 70%). In asimilar manner, the formations 106 ₁-106 _(F) may extend along a topportion of the lateral stabilizer 96 _(i).

In a variant, the uneven surfaces 102 ₁-102 _(U) may be able to bend.More specifically, as shown in FIG. 38, an uneven surface 102 _(i)extending along the top portion 107 of the traction projection 58 _(i)may bend relative to the bottom portion 109 of the traction projection58 _(i). This may be useful to further oppose the tendency of the track21 to skid due to a sloped terrain. For instance, this may enhance agrabbing action of the uneven surface 102 _(i) with the ground.

In another variant, with additional reference to FIGS. 79 to 81, atraction projection 58 i may comprise a plurality of lateral stabilizers296 ₁-296 _(S) configured to increase a lateral restrictive forceexerted by the traction projection 58 _(i). The traction projections 58₁-58 _(T) comprising the lateral stabilizers 296 ₁-296 _(S) may bedisposed in a staggered arrangement on the ground-engaging outer side 27of the track 21. In other words, at least a majority of (i.e., amajority or an entirety of) a given traction projection 58 _(i) may beoffset from an adjacent traction projection 58 _(j) (i.e., may notoverlap the adjacent traction projection 58 _(j)) in the widthwisedirection of the track 21.

Considering a cross-section of the traction projection 58 _(i) normal tothe thickness direction of the track 21, a dimension D₁ of each lateralstabilizer 296 _(i) in the longitudinal direction of the track 21 isgreater than a dimension D₂ of the lateral stabilizer 296 _(i) in thewidthwise direction of the track 21. For instance, in some embodiments,a ratio of the dimension D₁ of the lateral stabilizer 296 _(i) over thedimension D₂ of the lateral stabilizer 296 _(i) may be at least 3, insome cases at least 4, in some cases at least 5, and in some cases evenmore (e.g., 6).

The number of lateral stabilizers 296 ₁-296 _(S) per traction projection58 _(i) may be significant. For instance, in some embodiments, thetraction projection 58 _(i) may comprise at least three lateralstabilizers 296 ₁-296 _(S), in some cases at least four lateralstabilizers 296 ₁-296 _(S), in some cases at least five lateralstabilizers 296 ₁-296 _(S), and in some cases even more (e.g., six ormore).

In this example, the traction projection 58 _(i) also comprises aplurality of propulsive protrusions 298 ₁-298 _(P) configured to propelthe snowmobile 10 and disposed between adjacent ones of the lateralstabilizers 296 ₁-296 _(S). The propulsive protrusions 298 ₁-298 _(P)are longer in the widthwise direction of the track 21 than the lateralstabilizers 296 ₁-296 _(S). That is, a dimension D₃ of a propulsiveprotrusion 298 _(i) in the widthwise direction of the track 21 isgreater than the dimension D₂ of a lateral stabilizer 296 _(i).

The propulsive protrusions 298 ₁-298 _(P) may be shaped to improvetraction by causing the traction projection 58 i to contain snow orother ground matter on which the track 21 travels, as will be furtherdiscussed later. For instance, the propulsive protrusions 298 ₁-298 _(P)may be shaped to create a “scooping” effect of the traction projection58 _(i) on the snow or other ground matter on which the track 21travels. To that end, in this embodiment, the propulsive protrusions 298₁-298 _(P) are curved or otherwise shaped to respectively form aplurality of recesses 300 ₁-300 _(P) in which snow or other groundmatter may be more easily accumulated by the traction projection 58 i.For instance, in some examples, a recess 300 _(i) of a propulsiveprotrusion 298 _(i) may be shaped such that propulsive protrusion 298_(i) implements a “scoop” or “cup” to scoop or cup the snow or otherground matter. In particular, in this example, the propulsiveprotrusions 298 ₁-298 _(P) are curved along a plane that is normal tothe height direction of the track 21. For example, each of thepropulsive protrusions 298 ₁-298 _(P) may be U-shaped, V-shaped orshaped in any other suitable manner such as to form the recesses 300₁-300 _(P).

In some embodiments, selected ones of the propulsive protrusions 298₁-298 _(P) may be curved or otherwise shaped to form the recesses 300₁-300 _(P), while other ones of the propulsive protrusions 298 ₁-298_(P) may not be curved (e.g., flat). In other embodiments, all of thepropulsive protrusions 298 ₁-298 _(P) may not be curved (e.g., flat).

The traction projection 58 _(i) comprising the lateral stabilizers 296₁-296 _(S) and the propulsive protrusions 298 ₁-298 _(P) may have asignificant height HT. For instance, in some embodiments, the height HTof the traction projection 58 _(i) may be at least 1.5 inches, in somecases at least 1.75 inches, in some cases at least 2 inches, and in somecases even more (e.g., 2.5 or 3 inches). Such a configuration of thetraction projection 58 _(i) may be particularly useful in a mountainousenvironment as lateral forces exerted on the track 21 may be moresignificant.

Furthermore, in this example of implementation, as shown in FIG. 81, thetraction projection 58 _(i) comprises a flap 302 that can deflect (e.g.,bend) in response to a lateral force to increase a surface area of thetraction projection 58 _(i) that is transversal to the widthwisedirection of the track 21.

The flap 302 has a deflected state and an undeflected state. In itsundeflected state, the flap 302 is positioned transversally to thelongitudinal direction of the track 21 while in its deflected state, theflap 302 is positioned transversally to the widthwise direction of thetrack 21. In its undeflected state, a surface area of the flap 302transversal to the widthwise direction of the track 21 is smaller thanin the deflected state of the flap 302.

The flap 302 protrudes from a given lateral stabilizer 296 _(i) in adirection transverse to the longitudinal direction of the track 21. Theflap 302 may be disposed on an inner side of the traction projection 58_(i) (i.e., a side of the traction projection 58 _(i) that is closest toa center of the track 21) or on an outer side of the traction projection58 _(i) (i.e., a side of the traction projection 58 _(i) that is closestto a given one of the lateral edges 55 ₁, 55 ₂ of the track 21).

In this example, the flap 302 tapers in the height direction of thetrack 21. More specifically, a top portion of the flap 302 has a greaterextent in a direction transverse to the longitudinal direction of thetrack 21 than a bottom portion of the flap 302 such that an extent ofthe flap 302 in a direction transverse to the longitudinal direction ofthe track 21 decreases downwardly from the top portion of the flap 302.Moreover, in this example, the flap 302 is in contact with theground-engaging outer surface 31 of the track 21. In other examples, theflap 302 may not be in contact with the ground-engaging outer surface 31and may instead be solely in contact with the lateral stabilizer 296_(i). The flap 302 may be configured differently in other examples.

6. Traction Projections Configured to Contain Snow or Other GroundMatter

In some embodiments, as shown in FIGS. 79 to 85, a traction projection58 _(i) may be configured to contain snow or other ground matter fromthe ground to enhance traction. That is, the traction projection 58 _(i)comprises a containment space 304 to contain an amount of snow or otherground matter when the traction projection 58 _(i) engages the ground.This may help to compact the amount of snow or other ground mattercontained in the traction projection 58 _(i) and thus allow the tractionprojection 58 _(i) to press more on the compacted snow or other groundmatter, thereby generating greater tractive forces. For instance, thecontainment space 304 of the traction projection 58 _(i) may create a“scooping” or “cupping” action to scoop or cup the snow or other groundmatter. The scooping or cupping action may further be amplified when thetraction projection 58 i deforms as it engages the snow or other groundmatter and causes the containment space 304 to expand.

The containment space 304 of the traction projection 58 _(i) may besized such that the amount of snow or other ground matter it can containmay be relatively significant, as this may further improve traction.

In this embodiment, the containment space 304 of the traction projection58 _(i) comprises a plurality of containment voids 306 ₁-306 ₄ tocontain respective portions of the amount of snow or other ground mattercontained by the traction projection 58 _(i). More particularly, in thisembodiment, the traction projection 58 _(i) comprises the propulsiveprotrusions 298 ₁-298 _(P) and each of the containment voids 306 ₁-306 ₄is implemented by a respective one of the recesses 300 ₁-300 _(P)defined by the propulsive protrusions 298 ₁-298 _(P).

In this example, the recesses 300 ₁-300 _(P) implementing thecontainment voids 306 ₁-306 ₄ are distributed in a longitudinaldirection of the traction projection 58 _(i), which in this casecorresponds to the widthwise direction of the track 21. This allows thetraction projection 58 _(i) to contain the snow or other ground matterover a significant part of the length L of the traction projection 58_(i).

For instance, in some embodiments, the containment space 304 of thetraction projection 58 _(i) may occupy at least a majority (e.g., amajority or an entirety) of the length L of the traction projection 58_(i). For example, in some embodiments, the containment space 304 of thetraction projection 58 _(i) may occupy at least 60%, in some cases atleast 70%, in some cases at least 80%, in some cases at least 90%, andin some cases an entirety of the length L of the traction projection 58_(i).

In this regard, in this embodiment, each of the recesses 300 ₁-300 _(P)of the containment space 304 of the traction projection 58 _(i) mayoccupy a significant part of the length L of the traction projection 58_(i). For example, in some embodiments, a recess 300 _(i) of thecontainment space 304 of the traction projection 58 _(i) may occupy atleast 10%, in some cases at least 15%, in some cases at least 20%, insome cases at least 25%, and in some cases an even larger part of thelength L of the traction projection 58 _(i).

The containment space 304 of the traction projection 58 _(i) maytherefore be viewed as imparting an “effective” length L_(eff) of thetraction projection 58 _(i) that exceeds the (actual) length L of thetraction projection 58 _(i). Basically, the traction projection 58 _(i)may be viewed as generating more traction as if it was effectivelylonger. The effective length L_(eff) of the traction projection 58 _(i)can be measured by measuring a line that follows a shape of the tractionprojection 58 _(i) from the first longitudinal end 308 ₁ of the tractionprojection 58 _(i) to the second longitudinal end 308 ₂ of the tractionprojection 58 _(i). Conceptually, this can be viewed as that length thetraction projection 58 _(i) would have if it was straightened bystraightening segments that are non-straight in the longitudinaldirection of the traction projection 58 _(i) (which in this casecorresponds to the widthwise direction of the track 21), i.e., thepropulsive protrusions 298 ₁-298 _(P) defining the recesses 300 ₁-300_(P) in this example, such that they are straight in the longitudinaldirection of the traction projection 58 _(i).

For instance, in some embodiments, a ratio L_(eff)/L of the effectivelength L_(eff) of the traction projection 58 _(i) over the length L ofthe traction projection 58 _(i) may be at least 1.1, in some cases atleast 1.2, in some cases at least 1.3, in some cases at least 1.4, andin some cases even more.

Also, in this embodiment, the containment space 304 of the tractionprojection 58 _(i) may occupy at least a majority (e.g., a majority oran entirety) of the height H of the traction projection 58 _(i). Forexample, in some embodiments, the containment space 304 of the tractionprojection 58 _(i) may occupy at least 60%, in some cases at least 70%,in some cases at least 80%, in some cases at least 90%, and in somecases an entirety of the height H of the traction projection 58 _(i).

In this example of implementation, this may be particularly useful asthe height H of traction projection 58 _(i) is relatively significant.For instance, in some embodiments, the height H of the tractionprojection 58 _(i) may be at least 1.5 inches, in some cases at least1.75 inches, in some cases at least 2 inches, and in some cases evenmore (e.g., 2.5 or 3 inches).

In this regard, in this embodiment, each of the recesses 300 ₁-300 _(P)of the containment space 304 of the traction projection 58 _(i) mayoccupy at least a majority of the height H of the traction projection 58_(i). For example, in some embodiments, a recess 300 _(i) of thecontainment space 304 of the traction projection 58 _(i) may occupy atleast 60%, in some cases at least 70%, in some cases at least 80%, insome cases at least 90%, and in some cases an entirety of the height Hof the traction projection 58 _(i).

The amount of snow or other ground matter that can be contained in thecontainment space 304 of the traction projection 58 _(i) may thus besignificant. This can be measured as a volume V of the containment space304 of the traction projection 58 _(i) in which the amount of snow orother ground matter can be contained. For instance, in some embodiments,the volume V of the containment space 304 of the traction projection 58_(i) may be at least 0.8 in³, in some cases at least 1 in³, in somecases at least 1.2 in³, in some cases at least 1.4 in³ and in some caseseven more. For instance, in some cases, a ratio V/L of the volume V ofthe containment space 304 over the length L of the traction projection58 _(i) may be at least 0.3 in³/in, in some cases at least 0.5 in³/in,in some cases at least 0.8 in³/in, and in some cases even more.

In this embodiment, as shown in FIG. 83, the volume V of the containmentspace 304 of the traction projection 58 _(i) corresponds to a sum ofvolumes v₁-v₄ of the recesses 300 ₁-300 _(P) that can contain the snowor other ground matter. In this example, a volume v_(i) of a recess 300_(i) may be relatively significant. For instance, in some embodiments,the volume v_(i) of the recess 300 _(i) may be at least at least 10%, insome cases at least 15%, in some cases at least 20%, in some cases atleast 25%, and in some cases an even larger part of the volume V of thecontainment space 304 of the traction projection 58 _(i).

The propulsive protrusions 298 ₁-298 _(P) defining the recesses 300₁-300 _(P) of the containment space 304 of the traction projection 58_(i) may be shaped in any suitable way. In this embodiment, eachpropulsive protrusion 298 _(i) is curved to define its recess 300 _(i).More particularly, in this embodiment, the propulsive protrusion 298_(i) is generally U-shaped such that its recess 300 _(i) is alsoU-shaped. The recess 300 _(i) is open facing the ground as the tractionprojection 58 _(i) approaches the ground while the track 21 moves aroundthe track-engaging assembly 24 when the snowmobile 10 travels forward.

In this example of implementation, the traction projection 58 _(i),including the propulsive protrusions 298 ₁-298 _(P) and the lateralstabilizers 296 ₁-296 _(S), tapers in the thickness direction of thetrack 21. That is, a top portion 310 of the traction projection 58 _(i)has a smaller cross-sectional area than a bottom portion 312 of thetraction projection 58 _(i) adjacent to the outer surface 31 of thecarcass 35. This may help to strengthen the traction projection 58 _(i)given its height and its containment space 304 which are relativelysignificant.

More particularly, in this example of implementation, the top portion310 of the traction projection 58 _(i) is smaller in the longitudinaldirection of the track 21 than the bottom portion 312 of the tractionprojection 58 _(i). In this case, a top portion 314 of each lateralstabilizer 296 _(i) is smaller in the longitudinal direction of thetrack 21 than a bottom portion 316 of the lateral stabilizer 296 _(i),while a top portion 318 of each propulsive protrusion 298 _(i) issmaller in the longitudinal direction of the track 21 than a bottomportion 320 of the propulsive protrusion 298 _(i).

For instance, in some embodiments, a ratio of a dimension D_(1-b) of thebottom portion 316 of the lateral stabilizer 296 _(i) in thelongitudinal direction of the track 21 over a dimension D_(1-t) of thetop portion 314 of the lateral stabilizer 296 _(i) in the longitudinaldirection of the track 21 may be at least 1.1, in some cases at least1.2, in some cases at least 1.5, and in some cases even more (e.g., 2),and/or a ratio of a dimension D_(4-b) of the bottom portion 320 of thepropulsive protrusion 298 _(i) in the longitudinal direction of thetrack 21 over a dimension D_(4-t) of the top portion 318 of thepropulsive protrusion 298 _(i) in the longitudinal direction of thetrack 21 may be at least 1.1, in some cases at least 1.2, in some casesat least 1.5, and in some cases even more (e.g., 2).

Also, in some embodiments, the dimension D_(1-t) of the top portion 314of the lateral stabilizer 296 _(i) may be significantly greater than thedimension D_(4-t) of the top portion 318 of the propulsive protrusion298 _(i). For instance, in some cases, a ratio D_(1-t)/D_(4-t) of thedimension D_(1-t) of the top portion 314 of the lateral stabilizer 296_(i) over the dimension D_(4-t) of the top portion 318 of the propulsiveprotrusion 298 _(i) may be at least 2, in some cases at least 3, in somecases at least 4 and in some cases even more. This significantdifference between the dimensions D_(1-t) and D_(4-t) may allow thecontainment space 304 of the traction projection 58 _(i) to be biggerand thus compact more snow or other ground matter.

FIGS. 86 to 89 show a similar embodiment in which at least one of thetraction projections 58 ₁-58 _(T) of the track 21 is configured tocontain snow or other ground matter from the ground to enhance traction.The containment space 304 in this embodiment is reduced due to a smallersize of the propulsive protrusions 298 ₁-298 _(P).

Furthermore, as shown in FIG. 89, in some embodiments, a tractionprojection 58 _(i) may comprise a strengthener 315 for reinforcing agiven one of the propulsive protrusions 298 ₁-298 _(P). The strengthener315 is positioned such as to face away from the ground as the tractionprojection 58 _(i) approaches the ground while the track 21 moves aroundthe track-engaging assembly 24 when the snowmobile 10 travels forward.In other words, the strengthener 315 is disposed on a side of thetraction projection 58 _(i) that is opposite to the recesses 300 ₁-300_(P) of the containment space 304 of the traction projection 58 _(i).The strengthener 315 is disposed adjacent to a propulsive protrusion 298_(i) in the longitudinal direction of the track 21 such as to reinforcethe propulsive protrusion 298 _(i) when the propulsive protrusion 298_(i) engages the ground. This may help minimize wear of the tractionprojection 58 _(i). In this embodiment, the strengthener 315 comprisesan elongated rib that extends in the height direction of the track 21. Aheight of the strengthener 315 may be significant. For instance, theheight of the strengthener 315 may be equal to a majority or an entiretyof the height H of the traction projection 58 _(i). In this embodiment,the strengthener 315 is integral with the remainder of the tractionprojection 58 _(i) such that it is formed together with the tractionprojection 58 _(i).

The strengthener 315 may be configured in other ways in otherembodiments. For instance, the strengthener 315 may be shapeddifferently or its height may be less than a majority of the height H ofthe traction projection 58 _(i).

Furthermore, a given traction projection 58 _(i) may comprise more thanone strengthener 315. Notably, in this example of implementation, thetraction projection 58 _(i) comprises two strengtheners 315, eachstrengthener 315 being configured to reinforce a respective propulsiveprotrusion 298 _(i). Thus, in some embodiments, each propulsiveprotrusion 298 _(i) may be associated with a corresponding strengthener315, or one or more of the propulsive protrusions 298 ₁-298 _(P) may befree of a strengthener 315.

7. Adaptable Track

In some embodiments, as shown in FIG. 39, one or more components of thetrack 21 (e.g., the traction projections 58 ₁-58 _(T), the carcass 35,the drive/guide lugs 34 ₁-34 _(D)) may be adaptable in response to astimulus (e.g., temperature, humidity, loading, a signal, etc.) suchthat a state of a given component of the track 21 (e.g., a stiffness orother property; a shape; and/or any other characteristic of the givencomponent of the track) is variable in different conditions (e.g.,weather conditions; ground conditions, such as different types of snow,soil, etc.; and/or other conditions) in order to better perform inspecified conditions.

7.1 Adaptable Traction Projections

In some embodiments, as shown in FIG. 40, respective ones of thetraction projections 58 ₁-58 _(T) may be adaptable in response to astimulus (e.g., temperature, humidity, loading, a signal, etc.) suchthat a state of a traction projection 58 _(i) (e.g., a stiffness,hardness, or other property; a shape; and/or any other characteristic ofthe traction projection 58 _(i)) is variable in different conditions(e.g., weather conditions; ground conditions, such as different types ofsnow, soil, etc.; and/or other conditions) in order to better perform inspecified conditions. For example, in some embodiments, the tractionprojection 58 _(i) may be less stiff (e.g., softer) and/or less straight(e.g., bent) in powder snow (or other looser matter on the ground) thanin wet snow (or other denser matter on the ground).

7.1.1 Adaptable Stiffness

In some embodiments, as shown in FIG. 41, a stiffness of a tractionprojection 58 _(i) may be adaptable in response to a stimulus such thatthe traction projection 58 _(i) is stiffer in a first condition than ina second condition. That is, the stiffness of the traction projection 58_(i) changes based on the stimulus.

For instance, in some embodiments, the stiffness of the tractionprojection 58 _(i) may change based on a stimulus associated with anenvironmental parameter of an environment of the traction projection 58_(i).

For example, the stiffness of the traction projection 58 _(i) may belower when the traction projection 58 _(i) is in powder snow (or otherlooser matter on the ground) than when the traction projection 58 _(i)is in wet/spring snow (or other denser matter on the ground). Wet/springsnow is defined here as snow with a humidity of more than 3%.

More specifically, a ratio of the stiffness of the traction projection58 _(i) in powder snow over the stiffness of the traction projection 58_(i) in wet/spring snow may be at least 1.1, in some cases at least 1.2,in some cases at least 1.3, in some cases at least 1.5, in some cases atleast 2, and in some cases even more (e.g., 3 or more).

In some embodiments, the stiffness of the traction projection 58 _(i)may be lower when the humidity of the environment of the tractionprojection 58 _(i) is lower. For example, the stiffness of the tractionprojection 58 _(i) may be lower when the humidity of the snow that thetraction projection 58 _(i) engages is lower.

For instance, a ratio of the stiffness of the traction projection 58_(i) when the humidity has a given value over the stiffness of thetraction projection 58 _(i) when the humidity has a lower value than thegiven value may be at least 1.1, in some cases at least 1.2, in somecases at least 1.3, in some cases at least 1.5, in some cases at least2, and in some cases even more (e.g., 3 or more).

In some embodiments, the stiffness of the traction projection 58 _(i)may be lower when a temperature of the environment of the tractionprojection 58 _(i) is lower.

For instance, a ratio of the stiffness of the traction projection 58_(i) when the temperature has a given value over the stiffness of thetraction projection 58 _(i) when the temperature has a lower value thanthe given value may be at least 1.1, in some cases at least 1.2, in somecases at least 1.3, in some cases at least 1.5, in some cases at least2, and in some cases even more (e.g., 3 or more).

In some cases, the stiffness of the traction projection 58 _(i) may belower when snow (or other matter on the ground) that the tractionprojection 58 _(i) engages is softer. For instance, the stiffness of thetraction projection 58 _(i) may be lower when loading (e.g., impacts) onthe traction projection 58 _(i) is lower.

For instance, a ratio of the stiffness of the traction projection 58_(i) when the snow (or other matter on the ground) that the tractionprojection 58 _(i) engages has a given hardness over the stiffness ofthe traction projection 58 _(i) when the snow (or other matter on theground) that the traction projection 58 _(i) engages has a lowerhardness may be at least 1.1, in some cases at least 1.2, in some casesat least 1.3, in some cases at least 1.5, in some cases at least 2, andin some cases even more (e.g., 3 or more). The difference in hardness ofthe snow (or other matter on the ground) that the traction projection 58_(i) engages over which this ratio may apply may be no more than acertain value.

The stiffness of the traction projection 58 _(i) may be observed in anysuitable way in various embodiments.

For example, a material 114 of the traction projection 58 _(i) may varyin stiffness. For instance, a modulus of elasticity of the material 114of the traction projection 58 _(i) may vary based on the stimulus.

More particularly, a ratio of the modulus of elasticity of the material114 of the traction projection 58 _(i) in the first condition over themodulus of elasticity of the material 114 of the traction projection 58_(i) in the second condition may be at least 2, in some cases at least3, in some cases at least 4, and in some cases even more (e.g., 4.5 ormore). For instance, the modulus of elasticity may be Young's modulus orthe 100% modulus for the material 114 of the traction projection 58_(i).

In some embodiments, a hardness of the material 114 of the tractionprojection 58 _(i) may vary based on the stimulus.

For instance, a ratio of the hardness of the material 114 of thetraction projection 58 _(i) in the first condition over the hardness ofthe material 114 of the traction projection 58 _(i) in the secondcondition may be at least 1.1, in some cases at least 1.2, in some casesat least 1.3, in some cases at least 1.5, in some cases at least 2, andin some cases even more (e.g., 3 or more).

The material 114 of the traction projection 58 _(i) may be any suitablematerial. For example, in some embodiments, as shown in FIG. 42, thematerial 114 may be the rubber 41 of the traction projection 58 _(i). Inother embodiments, as shown in FIG. 43 the material 114 may interfacewith the rubber 41 of the traction projection 58 _(i). That is, thetraction projection 58 _(i) may comprise an adaptable member 116 thatincludes the material 114 and that interfaces with the rubber 41 of thetraction projection 58 _(i). The adaptable member 116 may be at leastpartially embedded in the rubber 41 of the traction projection 58 _(i).For example, the adaptable member 116 may be a core within the rubber 41of the traction projection 58 _(i).

In some embodiments, as shown in FIG. 44, the adaptable member 116 maybe at an outer surface of the rubber 41 of the traction projection 58_(i). For example, the adaptable member 116 may be a cover of thetraction projection 58 _(i) that covers the rubber 41 of the tractionprojection 58 _(i).

The adaptable member 116 and its material 114 may be provided in thetraction projection 58 _(i) in any suitable way. For instance, inembodiments in which the adaptable 116 is at least partially embeddedwithin the rubber 41 of the traction projection 58 _(i), the adaptablemember 116 may be formed in a first molding operation and thenovermolded by the rubber 41 of the traction projection 58 _(i) in asubsequent molding operation. Conversely, in embodiments in which theadaptable member 116 at the outer surface of the rubber 41 of thetraction projection 58 _(i), the rubber 41 may be formed in a firstmolding operation and then overmolded by the material 114 to form theadaptable member that covers the rubber 41 in a subsequent moldingoperation.

The adaptability of the stiffness of the traction projection 58 _(i) maybe implemented in any suitable way.

In some embodiments, the material 114 may have a property related to thestiffness, such as its modulus of elasticity and/or hardness, thatvaries considerably over a range of values of the stimulus to which thetraction projection 58 _(i) is expected to be exposed during use.

For instance, in some embodiments, the property related to the stiffnessof the material 114 may vary considerably over a range of temperaturesto which the traction projection 58 _(i) is expected to be exposedduring use. For example, the property related to the stiffness of thematerial 114 may vary between 0 and −30° C., in some cases between 0 and−20° C., and in some cases between 0 and −10° C.

In some embodiments, the property related to the stiffness of thematerial 114 may vary considerably over a range of humidity to which thetraction projection 58 _(i) is expected to be exposed during use. Forexample, the property related to the stiffness of the material 114 mayvary between 0% and 1% humidity, in some cases between 0% and 2%humidity, in some cases between 0% and 3% humidity, in some casesbetween 0% and 4% humidity, and in some cases between 0% and 5%humidity.

In some embodiments, the material 114 may be a rate-dependent material.That is, the property related to the stiffness of the material 114(e.g., modulus of elasticity and/or hardness of the material 114) mayvary based on a rate of change of a force applied on the tractionprojection 58 _(i). For example, the material 114 may comprise arate-dependent foam that is characterized as possessing a load-responsebehavior that resists sudden-movement rapid compression, yet is lessresistive to slow-movement compression.

Furthermore, in some embodiments, the material 114 may be anon-Newtonian material (i.e., a non-Newtonian fluid) having a viscositythat is dependent on shear rate or shear rate history.

7.1.2 Adaptable Shape

In some embodiments, as shown in FIG. 45, a shape of a tractionprojection 58 _(i) may be adaptable in response to a stimulus such thatthe shape of the traction projection 58 _(i) is different in a firstcondition than in a second condition. That is, the shape of the tractionprojection 58 _(i) changes based on the stimulus. This change in shapeof the traction projection 58 _(i) is distinct from any change in shapeof the traction projection 58 _(i) that may occur when the tractionprojection 58 _(i) contacts the ground and ceases to contact the ground.

For instance, the shape of the traction projection 58 _(i) may have agreater “packing” effect and/or “scooping” effect in powder snow than inwet/spring snow. For example, the shape of the traction projection 58_(i) may be less straight (e.g., bent) in powder snow (or other loosermatter on the ground) than in wet/spring snow (or other denser matter onthe ground). This may allow an improved floatation of the track 21 onpowder snow.

More particularly, as shown in FIG. 46, an angle θ₁ between a portion118 of the traction projection 58 _(i) and the height direction of thetrack 21 may be different in powder snow than in wet/spring snow. Forinstance, the angle θ₁ may be greater in powder snow than wet/springsnow. For example, a ratio of θ₁ in powder snow over θ₁ in wet/springsnow may be at least 1.1, in some cases at least 1.2, in some cases atleast 1.3, in some cases at least 1.5, in some cases at least 2, and insome cases even more (e.g., 3 or more).

In some cases, the portion 118 of the traction projection 58 _(i) may besubstantially vertical or nearly vertical (i.e., the angle θ₁ may be orbe close to 0°) in wet/spring snow. In other cases, the portion 118 ofthe traction projection 58 _(i) may be inclined in wet/spring snow, butmay be more inclined in powder snow.

For example, in wet/spring snow, the angle θ₁ may be no more than 30°,in some cases no more than 20°, in some cases no more than 10°, and insome cases 0°, while, in powder snow, the angle θ₁ may be at least 30°,in some case at least 40°, in some cases at least 50°, and in some caseseven more.

In some embodiments, as shown in FIG. 47, an angle θ₂ between theportion 118 of the traction projection 58 _(i) and another portion 120of the traction projection 58 _(i) that are adjacent in the heightdirection of the track 21 is different in powder snow than in wet/springsnow. The angle θ₂ between the portion 118 of the traction projection 58_(i) and the portion 120 of the traction projection 58 _(i) can bemeasured between respective tangents to the portion 118 of the tractionprojection 58 _(i) and the portion 120 of the traction projection 58_(i).

In some cases, the angle θ₂ is smaller in powder snow than in wet/springsnow. For instance, a ratio of the angle θ₂ in wet/spring snow over theangle θ₂ in powder snow may be at least 1.1, in some cases at least 1.2,in some cases at least 1.3, in some cases at least 1.5, in some cases atleast 2, and in some cases even more (e.g., 3 or more).

In other cases, the angle θ₂ may be greater in powder snow than inwet/spring snow. For instance, a ratio of the angle θ₂ in powder snowover the angle θ₂ in wet/spring snow may be at least 1.1, in some casesat least 1.2, in some cases at least 1.3, in some cases at least 1.5, insome cases at least 2, and in some cases even more (e.g., 3 or more).

In some cases, the traction projection 58 _(i) may be straight or nearlystraight (i.e., θ₂ may be or be close to 180°) in wet/spring snow. Inother cases, the traction projection 58 _(i) may be substantially bentbetween the first portion 118 of the traction projection 58 _(i) and thesecond portion 120 of the traction projection 58 _(i) in wet/springsnow, but may be more bent between the first portion 118 of the tractionprojection 58 _(i) and the second portion 120 of the traction projection58 _(i) in powder snow.

For instance, in wet/spring snow, the angle θ₂ may be between 140° and220°, in some cases between 150° and 210°, in some cases between 160°and 200°, and in some cases between 170° and 190°, while, in powdersnow, the angle θ₂ may be no more than 140°, in some case no more than130°, in some cases no more than 120°, and in some cases even less.

In some embodiments, the shape of the traction projection 58 _(i) may besuch that the height of the traction projection 58 _(i) is less inpowder snow (or other looser matter on the ground) than in wet/springsnow (or other denser matter on the ground). For instance, a ratio ofthe height of the traction projection 58 _(i) in wet/spring snow overthe height of the traction projection 58 _(i) in powder snow may be atleast 1.1, in some cases at least 1.2, in some cases at least 1.3, insome cases at least 1.5, in some cases at least 2, and in some caseseven more (e.g., 3 or more).

Moreover, in some embodiments, the shape of the traction projection 58_(i) may be such that a dimension G of the traction projection 58 _(i)in the longitudinal direction of the track 21 is greater in powder snow(or other looser matter on the ground) than in wet/spring snow (or otherdenser matter on the ground). For instance, a ratio of the dimension Gof the traction projection 58 _(i) in powder snow over the dimension Gof the traction projection 58 _(i) in wet/spring snow may be at least1.1, in some cases at least 1.2, in some cases at least 1.3, in somecases at least 1.5, in some cases at least 2, and in some cases evenmore (e.g., 3 or more).

The shape of the traction projection 58 _(i) may be less straight whenhumidity is lower. For instance, a ratio of the angle θ₁ when thehumidity has a given value over the angle θ₁ when the humidity has agreater value may be at least 1.1, in some cases at least 1.2, in somecases at least 1.3, in some cases at least 1.5, in some cases at least2, and in some cases even more (e.g., 3 or more). Moreover, a ratio ofthe angle θ₂ when the humidity has a given value over the angle θ₂ whenthe humidity has a lower value may be at least 1.1, in some cases atleast 1.2, in some cases at least 1.3, in some cases at least 1.5, insome cases at least 2, and in some cases even more (e.g., 3 or more).

The shape of the traction projection 58 _(i) may be less straight whentemperature is lower. For instance, a ratio of the angle θ₁ when thetemperature has a given value over the angle θ₁ when the temperature hasa greater value may be at least 1.1, in some cases at least 1.2, in somecases at least 1.3, in some cases at least 1.5, in some cases at least2, and in some cases even more (e.g., 3 or more). Moreover, a ratio ofthe angle θ₂ when the temperature has a given value over the angle θ₂when the temperature has a lower value may be at least 1.1, in somecases at least 1.2, in some cases at least 1.3, in some cases at least1.5, in some cases at least 2, and in some cases even more (e.g., 3 ormore).

The adaptability of the shape of the traction projection 58 _(i) may beimplemented in any suitable way.

For instance, as shown in FIG. 48, the traction projection 58 _(i) maycomprise a shape-changing member 122 to change the shape of the tractionprojection 58 _(i) in response to the stimulus. In one example ofimplementation, the shape-changing member 122 may comprise ashape-memory material 124 which has a “memory”. The shape-memorymaterial 124 is designed to acquire different shapes based on a stimulus(e.g., temperature, a magnetic or electric field, light, etc.).

In some embodiments, the shape-memory material 124 may comprise ashape-memory polymer. For example, the shape-memory polymer may be aphysically cross-linked shape-memory polymer such as linear blockcopolymers. For instance, in one example of implementation, theshape-memory polymer may be a polyesterurethane. The shape-memorypolymer may be any other suitably type of polymer in other embodiments(e.g., other plastics such as urethane).

In other embodiments, the shape-memory material 124 may comprise ashape-memory alloy. For example, the shape-memory alloy may be acopper-aluminium-nickel shape-memory alloy or a nickel-titanium alloy.The shape-memory alloy may be any other suitably type of alloy in otherembodiments (e.g., an iron-manganese-silicon alloy or acopper-zinc-aluminium alloy). Alternatively, the shape-memory material124 may comprise a woven material or a non-woven material. For example,the woven or non-woven material may comprise polyester, nylon, fiberglass, carbon fiber, or any other suitable woven or non-woven material.

In some embodiments, with additional reference to FIG. 49, theshape-changing member 122 may comprise an actuator 126 to change a shapeof the shape-changing member 122 in response to a signal. The actuator126 may be any suitable type of actuator such as an electric actuator, afluidic actuator or a pneumatic actuator. For example, the actuator 126may comprise a motor, a piston, or any other suitably type of actuator.

The signal transmitted to the actuator 126 of the shape-changing member122 may be an external signal received from a device 128 external to thetrack 21 over a link 130. In some embodiments, the device 128 may be awireless device such that the link 130 between the device 128 and theactuator 126 is a wireless link and the signal is transmitted wirelesslyover the link 130.

In some embodiments, the signal may be transmitted via contact with apart of the track 21 (e.g., via a port) such that the link 130 is awired link.

The device 128 may be any suitably type of device. For example, thedevice 128 may be a remote control, a smartphone, a computer, a personaldigital assistant (PDA), a tablet, etc. Moreover, in some embodiments,the device 128 may be an integral part of the snowmobile 10. Forexample, the device 128 may be a button (or any other type of interfaceelement) that is a part of the user interface 20 of the snowmobile 10.

In some embodiments, as shown in FIG. 50, the signal may be an internalsignal received from a device 132 within the track 21. For example, thedevice 132 may be a sensor. The device 132 may be provided in the track21 in any suitable way. For instance, the device 132 may be positionedwithin a mold and then overmolded by the elastomeric material(s) of thetrack 21. Moreover, the device 132 may be positioned in any suitablepart of the track 21. For instance, the device 132 may be placed withinthe traction projections 58 ₁-58 _(T), within the carcass 35 or withinthe drive/guide lugs 34 ₁-34 _(D).

7.2 Other Adaptable Components

In some embodiments, in addition to or instead of the tractionprojections 58 ₁-58 _(T), one or more other components of the track 21(e.g., the carcass 35, the drive/guide lugs 34 ₁-34 _(D)) may beadaptable in response to a stimulus such that a state of that componentof the track 21 (e.g., a stiffness or other property; a shape; and/orany other characteristic of the given component of the track) isvariable in different conditions (e.g., weather conditions; groundconditions, such as different types of snow, soil, etc.; and/or otherconditions) to better perform in specified conditions. Principlesdiscussed above in section 1.1 in respect of the traction projections 58₁-58 _(T) may be applied to adaptability of these one or more othercomponents of the track 21.

For instance, in some embodiments, the transversal stiffening rods 36₁-36 _(N) may have an adaptable response to a stimulus such that a stateof the transversal stiffening rods is variable in different conditions.This could allow the widthwise rigidity of the track 21 to vary inspecified conditions.

8. Adjustable Contact Patch

In some embodiments, as shown in FIG. 51, the track system 14 may beconfigured to adjust a size of the contact patch 59 of the track 21 withthe ground. This may be useful, for example, to make the contact patch59 of the track 21 larger when the snowmobile 10 travels on deep powdersnow or other soft grounds for enhanced floatation while making thecontact patch 59 of the track 21 smaller when the snowmobile 10 travelson packed snow or other hard grounds for facilitating steering and/orattaining higher operating speeds.

To that end, in this embodiment, the track system 14 comprises anadjustment mechanism 140 to change a configuration of the track-engagingassembly 24 in order to vary the size of the contact patch 59 of thetrack 21 with the ground. For example, in some embodiments, theadjustment mechanism 140 may be configured to change a position of oneor more of the rear idler wheels 26 ₁, 26 ₂, the lower roller wheels 28₁-28 ₆, and/or the sliding surfaces 77 ₁, 77 ₂ of the elongate support62 in order to vary the size of the contact patch 59 of the track 21with the ground.

In some cases, as shown in FIG. 52, the adjustment mechanism 140 maychange the configuration of the track-engaging assembly 24 while thelength of the track 21 remains constant (i.e., there is no change in thelength of the track 21), such that a shape of the track 21 around thetrack-engaging assembly 24 is changed to vary the size of the contactpatch 59 of the track 21 with the ground.

In other cases, as shown in FIGS. 53 to 57, the track 21 may comprise anadjustment mechanism 142 to adjust the length of the track 21 toaccommodate the adjustment mechanism 140 changing the configuration ofthe track-engaging assembly 24. For example, in some embodiments, theadjustment mechanism 142 of the track 21 may comprise a track section144 that is removable from the track 21 to vary the length of the track21. The adjustment mechanism 142 of the track 21 also comprisesconnectors 146 ₁, 146 ₂ for interconnecting the track section 144 to aremainder of the track 21. For instance, in some examples, the tracksection 144 may be replaceable with another track section 144* ofdifferent dimensions. In other examples, the track 21 may be closed byconnecting the connectors 146 ₁, 146 ₂ to one another without any tracksection therebetween.

The track section 144 comprises an inner side 148, a ground-engagingouter side 150, a front edge 152, a rear edge 154, and two lateral edges156 ₁, 156 ₂. The track section 144 comprises an elastomeric body 158underlying the inner side 148 and the ground-engaging outer side 150. Inview of its underlying nature, the elastomeric body 158 can be referredto as a “carcass”. The carcass 158 is elastomeric in that it compriseselastomeric material 161 (e.g., rubber). In this case, a plurality ofcomponents, including connectors 149 ₁, 149 ₂ and a plurality ofreinforcements are embedded in the elastomeric material 161 of thecarcass 158.

In this embodiment, the track section 144 comprises a plurality ofreinforcing cables 137 ₁-137 _(M) adjacent to one another and extendinggenerally in a longitudinal direction of the track section 144 (i.e., adirection from the front edge 152 to the rear edge 154 of the tracksection 144) to enhance strength in tension of the track section 144.The reinforcing cables 137 ₁-137 _(M) may be similar to the reinforcingcables 37 ₁-37 _(M). The track section 144 may also comprise a layer ofreinforcing fabric 143 similar to the layer of reinforcing fabric 43.

The ground-engaging outer side 150 of the track section 144 comprises anumber of traction projections 58 ₁-58 _(T) and the inner side 148 ofthe track section 144 comprises a number of drive/guide lugs 34 ₁-34_(D). In order to make a transition between the track section 144 andthe remainder of the track 21 as “seamless” as possible, in someembodiments, the traction projections 58 ₁-58 _(T) of the track section144 may form a pattern that complements a pattern of the tractionprojections 58 ₁-58 _(T) of the remainder of the track 21.

More particularly, in this embodiment, the front edge 152 and the rearedge 154 of the track 21 terminate at a midsection of a hole 40 _(i) andthus the ends of the remainder of the track 21 also terminate at amidsection of a hole 40 _(i).

The connectors 149 ₁, 149 ₂ are affixed to the front and rear edges 152,154 of the track section 144 and are configured to cooperate with theconnectors 146 ₁, 146 ₂ to form joints 155 ₁, 155 ₂. In this embodiment,as shown in FIG. 57, each joint 155 _(i) is an “alligator”-type joint.More particularly, the joint 155 _(i) comprises an elongatedinterlinking member 166 that interlinks a connector 149 _(i) with aconnector 146 _(i) to allow the track section 144 to hingedly moverelative to the remainder of the track 21 as the track 21 is driven bythe drive wheels 22 ₁, 22 ₂. In other words, in this embodiment, theinterlinking member 166 acts as a pin and the joint is basically a hingejoint. This motion enables a change in longitudinal curvature (i.e.,curvature along the longitudinal direction of the track 21) of a portionof the track 21 as it goes around the drive wheels 22 ₁, 22 ₂.

End fittings 172 ₁, 172 ₂ may be mounted to the interlinking member 166to ensure it does not move out of the connectors 146 ₁, 146 ₂, 149 ₁,149 ₂.

In embodiments where the holes 40 ₁-40 _(H) are not used to drive thetrack 21 (i.e., the drive/guide lugs 34 ₁-34 _(D) are used to drive thetrack 21), the interlinking member 166 may be a single interlinkingmember that extends from one lateral edge 156 ₁ to the other lateraledge 156 ₂ of the track section 144, as illustrated in FIG. 57. In otherembodiments, particularly where the holes 40 ₁-40 _(H) are used to drivethe track 21, the interlinking member 166 may comprise a plurality ofinterlinking elements engaging the connectors 146 ₁, 146 ₂, 149 ₁, 149 ₂and not traversing the holes 40 ₁-40 _(H). In such embodiments, endfittings may be provided at the ends of each interlinking element.

With additional reference to FIG. 58, each of the connectors 149 ₁, 149₂ comprises an anchoring portion 168 and a connecting portion 170. Theanchoring portion 168 of each connector 149 _(i) is embedded in therubber 161 of the carcass 158 and anchors the connector 149 _(i) to thecarcass 158, while the connecting portion 170 of the connector 149 _(i)lies outside the carcass 158 to be connected to a connecting portion ofa connector 146 _(i).

In this embodiment, as shown in FIG. 58, each connector 149 _(i)comprises a plurality of connection members 160 ₁-160 _(C) separate fromone another and disposed adjacent to one another. Each connection member160 _(i) comprises an anchoring part 162 and a connecting part 164. Theanchoring part 162 is embedded in the rubber 161 of the carcass 158 andanchors the connection member 160 _(i) to the carcass 158, while theconnecting part 164 lies outside the carcass 158 to be connected to theconnecting portion of a connector 146 _(i). Thus, the anchoring parts162 of the connection members 160 ₁-160 _(C) of the connector 149 _(i)collectively constitute the anchoring portion 168 of the connector 149_(i).

Each of the connection members 160 ₁-160 _(C) is coupled to a subset ofthe reinforcing cables 137 ₁-137 _(M). More specifically, as shown inFIG. 59 the anchoring part 162 of each connection member 160 _(i)defines a plurality of openings 176 ₁-176 _(P) for receiving therein thecorresponding subset of reinforcing cables 137 ₁-137 _(M). Theconnecting part 164 of each connection member 160 _(i) defines anopening 174 to receive the elongated interlinking member 166.

The adjustment mechanism 140 to change the configuration of thetrack-engaging assembly 24 may be implemented in any suitable way.

8.1 Toolless Adjustment

In some embodiments, as shown in FIG. 60, the adjustment mechanism 140may be configured to change the configuration of the track-engagingassembly 24 toollessly, i.e., without use of any tool (e.g., wrench,screwdriver, etc.) separate from and external to the track system 14that has to be mechanically engaged with the track-engaging assembly 24.More particularly, in this embodiment, the adjustment mechanism 140 isconfigured to change the configuration of the track-engaging assembly 24in response to a command. This command, which may be referred to as an“adjustment command”, is provided toollessly (i.e., without use of anytool separate from and external to the track system 14 that has to bemechanically engaged with the track-engaging assembly 24). In somecases, the adjustment command may be provided by the user of thesnowmobile 10, whereas, in other cases, the adjustment command may begenerated automatically.

8.1.1. Adjusting Configuration of Track-Engaging Assembly with MinimalUser Input

In some embodiments, as shown in FIGS. 61 to 63, the adjustmentmechanism 140 for changing the configuration of the track-engagingassembly 24 may be manually operated to allow changing the configurationof the track-engaging assembly 24 through minimal user input. In otherwords, the adjustment mechanism 140 may facilitate a manual adjustmentof the configuration of the track-engaging assembly 24. To that end, theadjustment command is inputtable by the user of the snowmobile 10 via auser interface 180 configured to allow the user to adjust theconfiguration of the track-engaging assembly 24. In this embodiment, theadjustment mechanism 140 comprises the user interface 180.

As shown in FIG. 62, the user interface 180 comprises an input device184 that the user can act upon to adjust the track-engaging assembly 24.The input device 184 may be implemented in any suitable way. Forexample, in some embodiments, the input device 184 may comprise amechanical input element, such as a lever, a switch, a button, a dial, aknob, a manual screw, a clamp, or any other physical element that theuser can act upon to adjust the track-engaging assembly 24. In otherembodiments, the input device 184 may comprise a virtual input element,such as a virtual button or other virtual control, of a graphical userinterface (GUI) displayed on a screen.

The user interface 180 may also comprise an output device 186 that canconvey information about the track-engaging assembly 24 to the user inorder to facilitate the adjustment of the track-engaging assembly 24.For example, in some embodiments, the output device 186 may comprise adisplay for displaying information to the user of the snowmobile 10. Forinstance, the display may be configured to display the size of thecontact patch 59 of the track 21, or any other parameter related to thetrack system 14.

When the user acts upon the input device 184 of the user interface 180,the adjustment command is conveyed to the adjustment mechanism 140 toadjust the track-engaging assembly 24. The adjustment mechanism 140comprises an actuator 188 for adjusting the track-engaging assembly 24based on the adjustment command.

In this embodiment, as will be described in more detail below, theactuator 188 comprises a mechanical actuator. The actuator 188 maycomprise other types of actuators in other embodiments. For instance, asshown in FIGS. 67 and 68, in some embodiments, the actuator 188 maycomprise an electromechanical actuator (e.g., a linear actuator) or afluidic actuator (e.g., a hydraulic or pneumatic actuator).

In some embodiments, the adjustment command may be conveyed as amechanical action. For instance, the adjustment command may constitute amechanical motion that is transmitted via the actuator 188 of theadjustment mechanism 140. In some cases, the adjustment command may beconveyed via a linkage or any other mechanical transmission.

In other embodiments, the adjustment command may be conveyed as asignal. For instance, the adjustment command may be conveyed as anelectrical signal configured to be received by an electromechanicalactuator.

With additional reference to FIG. 63, in this embodiment, the inputdevice 184 comprises a lever configured to be acted upon by theadjustment command of the user while the actuator 188 comprises a rotarymechanism 190 that effects an adjustment of the size of the contactpatch 59 of the track 21 based on the adjustment command that the usertransmits to the lever 184.

The rotary mechanism 190 is configured to enable the rear idler wheels26 ₁, 26 ₂ to pivot about a pivot axis such as to change theconfiguration of the track-engaging assembly 24. To that end, in thisembodiment, the rotary mechanism 190 comprises a tube 192, a shaft 194engaged with and rotatable relative to the tube 192, and a pair oflinking members 196 ₁, 196 ₂ that connects the rotary mechanism 190 tothe rear idler wheels 26 ₁, 26 ₂.

The tube 192 extends along a longitudinal axis 198 that is generallyparallel to the widthwise direction of the track system 14. The tube 192is fixedly connected to the rails 44 ₁, 44 ₂ of the elongate support 62(e.g., via a pressure fit) and receives the shaft 194 in its hollowinterior. Moreover, the tube 192 comprises a slot 200 extending in itscircumferential direction.

The shaft 194 is received within the tube 192 and is rotatable relativeto the tube 192 about its longitudinal axis 198 (which can be referredto as a pivot axis). For instance, bearings may be disposed between anouter surface of the shaft 194 and an inner surface of the tube 192 toallow the shaft 194 to rotate relative to the tube 192. The lever 184 isconnected to the shaft 194 (e.g., via a threaded connection) such thatactuation of the lever 184 results in a rotation of the shaft 194 aboutthe pivot axis 198.

The linking members 196 ₁, 196 ₂ connect the rotary mechanism 190 to therear idler wheels 26 ₁, 26 ₂. More particularly, the linking members 196₁, 196 ₂ are connected to and supported by the shaft 194. The connectionbetween the linking members 196 ₁, 196 ₂ and the shaft 194 is a fixedconnection that prevents rotation of the linking members 196 ₁, 196 ₂relative to the shaft 194. For example, the linking members 196 ₁, 196 ₂may be connected to the shaft 194 via a pressure fit, welding, afastener, or any other suitable method. The linking members 196 ₁, 196 ₂are also fixedly connected to an axle 202 of the rear idler wheels 26 ₁,26 ₂.

The lever 184 traverses the tube 192 via its slot 200. In thisembodiment, as will be explained in more detail below, the slot 200allows at least two positions of the lever 184. More specifically, inthis embodiment, the slot 200 comprises two open portions 204 forreceiving the lever 184 and a restricting portion 206 between the openportions 204 for restricting passage of the lever 184. The open portions204 of the slot 200 accommodate the size of the lever 184 (e.g., itsdiameter) such that there is a clearance between a periphery of the slot200 and the lever 184. Conversely, the restricting portion 206 of theslot 200 is configured to bar the passage of the lever 184 from one openportion to the other. In other words, a sizing of the restrictingportion 206 is such that the lever 184 does not readily pass from oneopen portion 204 to the other. For example, the sizing of therestricting portion 206 may be equal to or less than the size of thelever 184. To that end, in this embodiment, a resilient member 208 maybe provided at the restricting portion 206 to restrict the passage ofthe lever 184. The resilient member 208 is deformable from a firstconfiguration to a second configuration in response to a load and canrecover its first configuration upon removal of the load. In thisexample, the resilient member 208 comprises two resilient elements 210₁, 210 ₂ opposite one another, each resilient element 210 _(i)comprising an elastomeric material such as rubber.

Thus, in use, the operator of the snowmobile 10 actuates the lever 184to move it from one open portion 204 of the slot 200 to the other openportion. The restricting portion 206 of the slot 206 allows the passageof the lever 184 due to the force applied by the operator on the lever184 under which the resilient member 208 deforms to allow passage of thelever 184. This causes a rotation of the shaft 194 about the pivot axis198 which in turn causes the linking members 196 ₁, 196 ₂ and the rearidler wheels 26 ₁, 26 ₂ to pivot about the pivot axis 198. In thismanner, the configuration of the track-engaging assembly 24 can bechanged to reduce the contact patch 59 of the track 21.

In a variant, the user interface 180 may be a part of the snowmobile 10rather than the track system 14. For instance, the user interface 180may be a part of the user interface 20 of the snowmobile 10 (e.g., apart of the instrument panel of the snowmobile 10). For example, in somecases, the input device 184 of the user interface 180 may comprise aswitch on the instrument panel of the snowmobile 10 that can be actuatedby the user to transmit an adjustment command to the actuator 188 whichadjusts the track-engaging assembly 24. In such cases, the actuator 188may not be a purely mechanical actuator but rather an electromechanicalactuator or a fluidic actuator that is configured to receive theadjustment command provided as a signal (i.e., an electrical signal).

8.1.2. Adjusting Configuration of Track-Engaging Assembly Automatically

In some embodiments, as shown in FIG. 69, the adjustment mechanism 140for adjusting the track-engaging assembly 24 may enable an automaticadjustment of the track-engaging assembly 24, i.e., adjustment of thetrack-engaging assembly 24 without user input. To that end, theadjustment command is automatically generated by a controller 250. Inthis embodiment, the adjustment mechanism 140 comprises the controller250.

For instance, in this embodiment, as shown in FIG. 70, with thecontroller 250, the adjustment mechanism 140 may comprise an automaticadjustment system 215 configured to automatically adjust thetrack-engaging assembly 24.

The automatic adjustment of the track-engaging assembly 24 may beeffected based on information regarding the track system 14. Forexample, in some embodiments, the information regarding the track system14 may include information regarding the environment of the track system14, such as, for example, the profile (e.g., the slope or steepness orthe levelness) of the ground beneath the track system 14, the compliance(e.g., softness or hardness) of the ground beneath the track system 14,and/or any other parameter that pertains to the environment of the tracksystem 14.

In this embodiment, as shown in FIG. 71, the controller 250 for theautomatic adjustment system 215 comprises a sensor 212 configured tosense one or more parameters relating to the track system 16 _(i) and aprocessing apparatus 214 configured to convey the adjustment command toadjust the track-engaging assembly 24 based on these one or moreparameters relating to the track system 14. The adjustment mechanism 100comprises an actuator 216 for adjusting the track-engaging assembly 24based on the adjustment command from the processing apparatus 214.

The sensor 212 is configured to sense one or more parameters relating tothe track system 14. For instance, as discussed above, examples of oneor more parameters relating to the track system 14 that can be sensed bythe sensor 212 include the profile of the ground beneath the tracksystem 14 and/or the compliance of the ground beneath the track system14.

To that end, as shown in FIG. 72, the sensor 212 may comprise one ormore sensing elements 218 to sense these one or more parameters relatingto the track system 14. For example, in some embodiments, to sense theprofile of the ground beneath the track system 14, a sensing element 252may be a gyroscope; and to sense the compliance of the ground beneaththe track system 14, a sensing element 252 may be an accelerometer.

In some embodiments, the sensor 212 may include sensor elements that areintegral to the snowmobile 10. That is, the sensor 212 may includesensor elements that are standard sensor elements installed on thesnowmobile 10 by its manufacturer. For example, the sensor 212 mayinclude a speedometer of the snowmobile 10, a transmission state sensorof the snowmobile 10, and/or any other suitable sensor element of thesnowmobile 10.

The sensor 212 is configured to communicate the parameter(s) it sensesto the processing apparatus 214 via a link 220. To that end, the sensor152 comprises a transmitter 222 for transmitting the parameter(s)relating to the track system 14 to the processing apparatus 214, whichcomprises a receiver 224 to receive the sensor signal from the sensor212.

The transmitter 222 of the sensor 212 and the receiver 224 of theprocessing apparatus 154 may establish the link 220 between one anotherin any suitable way. In this embodiment, the link 220 is a wireless linksuch that the sensor 212 and the processing apparatus 214 are connectedwirelessly. Thus, in this embodiment, the transmitter 222 of the sensor212 is a wireless transmitter that can wirelessly transmit the sensorsignal and the receiver 224 of the processing apparatus 214 is awireless receiver that can wirelessly receive the sensor signal. Forexample, the transmitter 222 and the receiver 224 may implementradio-frequency identification (RFID) technology. In such an example,the transmitter 222 may be an RFID tag while the receiver 224 may be anRFID reader.

The sensor signal indicative of the parameter(s) of the track system 14may be issued by the sensor 212 in any suitable manner.

In this embodiment, the sensor 212 is configured to issue the inputsignal indicative of the parameter(s) of the track system 14 to theprocessing apparatus 214 autonomously. For instance, the transmitter 222of the sensor 212 may issue the input signal indicative of theparameter(s) of the track system 14 to the processing apparatus 214repeatedly (e.g., periodically or at some other predetermined instants).This may allow a short response time for adjustment of thetrack-engaging assembly 24.

In other embodiments, the processing apparatus 214 may be configured toissue an interrogation signal directed to the sensor 212, which isconfigured to issue the sensor signal to the processing apparatus 214 inresponse to the interrogation signal. In such embodiments, theprocessing apparatus 214 may comprise a transmitter 226 to transmit theinterrogation signal to the sensor 212, which comprises a receiver 228to receive the interrogation signal. In this case, the transmitter 226of the processing apparatus 214 is a wireless transmitter to wirelesslytransmit the interrogation signal and the receiver 228 of the sensor 212is a wireless receiver to wirelessly receive the interrogation signal.In some examples of implementation, the transmitter 222 and the receiver228 of the sensor 212 may be implemented by a transceiver and/or thetransmitter 226 and the receiver 224 of the processing apparatus 214 maybe implemented by a transceiver.

The processing apparatus 214 is configured to issue the adjustmentcommand relating to the adjustment of the track-engaging assembly 24based on the sensor signal from the sensor 212 and possibly other inputand/or information. More specifically, in this embodiment, theprocessing apparatus 214 issues the adjustment command in the form of asignal (e.g., an electrical signal) directed to the actuator 216 of theautomatic adjustment system 215 to control the configuration of thetrack-engaging assembly 24 based on the sensed parameter(s) of the tracksystem 14. In other embodiments, the adjustment command issued by theprocessing apparatus 214 may also be directed to an output device (e.g.,a display) for outputting information regarding the configuration of thetrack-engaging assembly 24 to the user of the snowmobile 10.

In some embodiments, the processing apparatus 214 may processinformation from sources other than the sensor 212 to determine theadjustment command. For instance, in some embodiments, the processingapparatus 214 may process information from an engine control unit (ECU)of the snowmobile 10 to infer that an adjustment of the track-engagingassembly is desirable. In such embodiments, the adjustment commandissued by the processing apparatus 214 is therefore unrelated to sensorsmonitoring parameters of the track system 14.

In this embodiment, as shown in FIG. 73, the processing apparatus 214comprises an interface 230, a processing portion 232, and a memoryportion 234, which are implemented by suitable hardware and/or software.

The interface 230 comprises one or more inputs and outputs allowing theprocessing apparatus 214 to receive input signals from and send outputsignals to other components to which the processing apparatus 214 isconnected (i.e., directly or indirectly connected). For example, in thisembodiment, an input of the interface 230 is implemented by the wirelessreceiver 224 to receive the sensor signal from the sensor 212. An outputof the interface 230 is implemented by a transmitter 236 to transmit theadjustment command to the actuator 216. In some embodiments, anotheroutput of the interface 230 is implemented by the wireless transmitter226 to transmit the interrogation signal to the sensor 212.

The processing portion 232 comprises one or more processors forperforming processing operations that implement functionality of theprocessing apparatus 214. A processor of the processing portion 232 maybe a general-purpose processor executing program code stored in thememory portion 234. Alternatively, a processor of the processing portion232 may be a specific-purpose processor comprising one or morepreprogrammed hardware or firmware elements (e.g., application-specificintegrated circuits (ASICs), electrically erasable programmableread-only memories (EEPROMs), etc.) or other related elements.

The memory portion 234 comprises one or more memories for storingprogram code executed by the processing portion 232 and/or data usedduring operation of the processing portion 232. A memory of the memoryportion 234 may be a semiconductor medium (including, e.g., asolid-state memory), a magnetic storage medium, an optical storagemedium, and/or any other suitable type of memory. A memory of the memoryportion 234 may be read-only memory (ROM) and/or random-access memory(RAM), for example.

In some embodiments, the processing apparatus 214 may determine theadjustment command at least in part based on information contained inthe memory portion 234. For instance, the memory portion 234 of theprocessing apparatus 214 may contain information associating differentvalues of a parameter relating to the track system 14 and/or thesnowmobile 10 with different values of a given parameter of thetrack-engaging assembly 24. For example, the memory portion 234 of theprocessing apparatus 214 may associate ranges of compliance of theground beneath the track system 14 with a given configuration of thetrack-engaging assembly 24. Thus, upon receiving the sensor signalindicative of the compliance of the ground beneath the track system 14,the processing apparatus 214 may consult its memory portion 234 toassociate the compliance of the ground beneath the track system 14 witha corresponding configuration of the track-engaging assembly 24. Asimilar approach may be undertaken for other sensed parameters of thetrack system 14 and/or the snowmobile 10.

In some embodiments, two or more elements of the processing apparatus214 may be implemented by devices that are physically distinct from oneanother and may be connected to one another via a bus (e.g., one or moreelectrical conductors or any other suitable bus) or via a communicationlink which may be wired, wireless, or both. In other embodiments, two ormore elements of the processing apparatus 214 may be implemented by asingle integrated device.

The processing apparatus 214 may be implemented in any other suitableway in other embodiments.

The adjustment command that is issued by the processing apparatus 214relates to the adjustment of the configuration of the track-engagingassembly 24. For instance, in this embodiment, with additional referenceto FIG. 74, the adjustment command may cause the actuator 216 toincrease and/or decrease the contact patch 59 of the track 21. Forinstance, the adjustment command is configured to cause the actuator 216to change an angular orientation of the axle 202 of the rear idlerwheels 26 ₁, 26 ₂ about the pivot axis 198 based on one or more sensedparameters of the track system 14. For example, in this particularembodiment, the actuator 216 is configured to adjust the angularorientation of the axle 202 of the rear idler wheels 26 ₁, 26 ₂ aboutthe pivot axis 198 based at least in part on the compliance of theground beneath the track system 14. In some embodiments, the actuator216 may alternatively or additionally adjust the angular orientation ofthe axle 202 about the pivot axis 198 based on the softness or hardnessof the ground, on the slope or steepness of the ground, and/or any othersuitable parameters relating to the track system 14.

More specifically, in this embodiment, as will be described in moredetail below, the actuator 216 is configured to rotate the shaft 194such as to cause the axle 202 of the rear idler wheels 26 ₁, 26 ₂ torotate about the pivot axis 198.

The actuator 216 may be implemented in various ways. For instance, inthis embodiment, the actuator 216 is an electromechanical actuator. Inother embodiments, the actuator 216 may be any other suitable type ofactuator such as a mechanical actuator or a fluidic actuator (e.g., ahydraulic or pneumatic actuator).

In this embodiment, as shown in FIG. 75, the actuator 216 is a rotaryactuator that is capable of inducing rotary motion. The actuator 216comprises a motor (not shown) that is responsive to the adjustmentcommand transmitted by the processing apparatus 214.

The actuator 216 comprises a shaft-receiving aperture that is driven bythe motor of the actuator 216. Such rotary actuators are well known inthe art and their operation will thus not be further described here. Theactuator 216 is mounted on the shaft 194 via its shaft-receivingaperture which can cause rotation of the shaft 194 about the pivot axis198 of the tube 192. In this example, two actuators are used to rotatethe shaft 194. In other examples, a single actuator may be used.

Thus, in use, the sensor 212 senses a parameter relating to the tracksystem 14 and issues a signal indicative of the value of the parameterto the processing apparatus 214 which in turn processes the sensorsignal to determine and issue the adjustment command to the actuator216. In this embodiment, the adjustment command relates to the actuationof the shaft 194 to effect a displacement of the axle 202 which, asdescribed above, modifies the configuration of the track-engagingassembly 24.

In this embodiment, the actuator 216 offers a continuous range ofadjustment of the angular orientation of the rear idler wheels 26 ₁, 26₂ about the pivot axis 198. In other words, the rear idler wheels 26 ₁,26 ₂ may occupy an infinite number of distinct angular positions withina range of displacement of the shaft 194. As such, the track-engagingassembly 24 may have one of an infinite number of differentconfigurations in accordance to the position of the rear idler wheels 26₁, 26 ₂.

In a variant, the controller 250 may be part of the snowmobile 10 ratherthan the track system 14. For example, the controller 250 may be part ofan ECU of the snowmobile 10 or may be part of any other controller ofthe snowmobile 10.

In another variant, as shown in FIG. 76, the controller 250 may be partof a communication device 260 external to the snowmobile 10). Examplesof embodiments of the communication device 260 include but are notlimited to a smartphone, a personal digital assistant (PDA), a tablet, asmart watch, a computer, or any other suitable communication device. Forinstance, in this variant, the controller 250 of the communicationdevice 260 may sense the speed of the snowmobile 10 based on GPS datarelayed to the communication device 260. The processing apparatus 214 ofthe controller 250 may consequently determine the adjustment commandbased on the sensed profile of the ground (i.e., terrain roughness,unevenness) based on data provided by an accelerometer of thecommunication device 260. The processing apparatus 214 may consequentlydetermine the adjustment command based on the accelerometer data andtransmit the adjustment command to the actuator 216 to adjust thetrack-engaging assembly 24 accordingly.

8.2 Tool-Based Adjustment

In some embodiments, as shown in FIG. 77, the adjustment mechanism 140may be configured to change the configuration of the track-engagingassembly 24 using one or more tools (e.g., wrench, screwdriver, etc.).

For instance, in some embodiments, the adjustment mechanism 140 mayallow the operator of the snowmobile 10 to adjust the positioning of thelinking members 196 ₁, 196 ₂ with a tool such as to modify theconfiguration of the track-engaging assembly 24.

For example, in such embodiments, the adjustment mechanism 140 maycomprise a shaft 240 extending along a longitudinal axis 245 that istransversal to the rails 44 ₁, 44 ₂. The shaft 240 is connected to therails 44 ₁, 44 ₂ (e.g., via a pressure fit) and comprises a plurality offastening apertures 242 at its longitudinal end portions for securingthe linking members 196 ₁, 196 ₂ to the shaft 240. Each linking member196 _(i) comprises an opening 244 (e.g., a hole) for receiving the shaft240. Enough clearance may be provided between the opening 244 and theshaft 240 to allow the shaft to rotate within the opening 244. Thelinking member 196 _(i) further comprises an aperture 246 extending froman outer periphery of the linking member 196 _(i) to the inner peripheryof the linking member 196 _(i) defined by the opening 244.

As shown in FIG. 78, when the aperture 246 of the linking member 196_(i) is aligned with one of the fastening apertures 242 of the shaft240, a fastener 248 is inserted through the aperture 246 and intoengagement with the aligned fastening aperture 242. In this example, thefastener 248 is a set screw and the fastening apertures 242 are threadedholes such that a tool (e.g., a screwdriver or a hex key) is used todrive the fastener into engagement with a respective one of thefastening apertures 242. Engaging the fastener 248 with a differentfastening aperture 242 modifies the orientation of the linking member196 i. More particularly, the linking member 196 _(i) is rotated aboutthe longitudinal axis 245 (which may be referred to as a pivot axis) ofthe shaft 240. This causes the axle 202 and thus the rear idler wheels26 ₁, 26 ₂ to rotate about the pivot axis 245 such as to change theconfiguration of the track-engaging assembly 24.

While in embodiments considered above the track system 14 is part of thesnowmobile 10, a track system constructed according to principlesdiscussed herein may be used as part of other off-road vehicles in otherembodiments. For example, in some embodiments, a track systemconstructed according to principles discussed herein may be used as partof an all-terrain vehicle (ATV), as part of an agricultural vehicle(e.g., a tractor, a harvester, etc.), as part of a construction vehicle,forestry vehicle or other industrial vehicle, or as part of a militaryvehicle.

Certain additional elements that may be needed for operation of someembodiments have not been described or illustrated as they are assumedto be within the purview of those of ordinary skill in the art.Moreover, certain embodiments may be free of, may lack and/or mayfunction without any element that is not specifically disclosed herein.

Any feature of any embodiment discussed herein may be combined with anyfeature of any other embodiment discussed herein in some examples ofimplementation.

Although various embodiments and examples have been presented, this wasfor the purpose of describing, but not limiting, the invention. Variousmodifications and enhancements will become apparent to those of ordinaryskill in the art and are within the scope of the invention, which isdefined by the appended claims.

1. A track for traction of a vehicle, the track being movable around atrack-engaging assembly comprising a drive wheel to drive the track, thetrack comprising: a carcass comprising a ground-engaging outer surfacefor engaging the ground and an inner surface opposite to theground-engaging outer surface; and a plurality of traction projectionsprojecting from the ground-engaging outer surface; wherein: a thicknessof the carcass from the ground-engaging outer surface to the innersurface is no more than 0.20 inches; and a ratio of a widthwise rigidityof the carcass over a longitudinal rigidity of the carcass is at least1.5.
 2. The track of claim 1, wherein the thickness of the carcass is nomore than 0.18 inches.
 3. The track of claim 1, wherein the thickness ofthe carcass is no more than 0.16 inches.
 4. The track of claim 1,wherein the ratio of the widthwise rigidity of the carcass over thelongitudinal rigidity of the carcass is at least
 2. 5. (canceled)
 6. Thetrack of claim 1, wherein the ratio of the widthwise rigidity of thecarcass over the longitudinal rigidity of the carcass is at least
 3. 7.The track of claim 1, wherein: the carcass comprises elastomericmaterial and a reinforcement disposed within the elastomeric material;and a ratio of a bending stiffness of the reinforcement in a widthwisedirection of the track over a bending stiffness of the reinforcement ina longitudinal direction of the track is at least
 2. 8. The track ofclaim 7, wherein the ratio of the bending stiffness of the reinforcementin the widthwise direction of the track over the bending stiffness ofthe reinforcement in the longitudinal direction of the track is at least3.
 9. The track of claim 7, wherein the ratio of the bending stiffnessof the reinforcement in the widthwise direction of the track over thebending stiffness of the reinforcement in the longitudinal direction ofthe track is at least
 4. 10. The track of claim 7, wherein the ratio ofthe bending stiffness of the reinforcement in the widthwise direction ofthe track over the bending stiffness of the reinforcement in thelongitudinal direction of the track is at least
 5. 11. The track ofclaim 7, wherein the reinforcement comprises a layer of reinforcingcables.
 12. The track of claim 7, wherein the reinforcement comprises alayer of reinforcing fabric.
 13. The track of claim 1, wherein: thecarcass comprises elastomeric material and a reinforcement disposedwithin the elastomeric material; a ratio of a modulus of elasticity ofthe reinforcement in a longitudinal direction of the track over thethickness of the track is at least 1 GPa/in; and a ratio of a modulus ofelasticity of the reinforcement in a widthwise direction of the trackover the thickness of the track is at least 5 GPa/in. 14.-40. (canceled)41. A track for traction of a vehicle, the track being movable around atrack-engaging assembly comprising a drive wheel to drive the track, thetrack comprising: a ground-engaging outer surface for engaging theground and an inner surface opposite to the ground-engaging outersurface; a plurality of traction projections projecting from theground-engaging outer surface; and a plurality of slide members forsliding against the track-engaging assembly; wherein a spacing oflongitudinally-adjacent ones of the slide members in a longitudinaldirection of the track is at least one-fifth of a length of the track.42. The track of claim 41, wherein the spacing oflongitudinally-adjacent ones of the slide members in the longitudinaldirection of the track is at least one-quarter of the length of thetrack.
 43. The track of claim 41, wherein the spacing oflongitudinally-adjacent ones of the slide members in the longitudinaldirection of the track is at least one-third of the length of the track.44. The track of claim 41, wherein the spacing oflongitudinally-adjacent ones of the slide members in the longitudinaldirection of the track is at least half of the length of the track. 45.The track of claim 41, wherein the slide members are arranged such thatno more than three of the slide members can contact the track-engagingassembly at any given instant.
 46. The track of claim 41, wherein theslide members are arranged such that no more than two of the slidemembers can contact the track-engaging assembly at any given instant.47. The track of claim 41, wherein the slide members are arranged suchthat no more than one of the slide members can contact thetrack-engaging assembly at any given instant. 48.-59. (canceled)
 60. Atrack for traction of a vehicle, the track being movable around atrack-engaging assembly comprising a drive wheel to drive the track, thetrack comprising: a ground-engaging outer surface for engaging theground and an inner surface opposite to the ground-engaging outersurface; a plurality of traction projections projecting from theground-engaging outer surface; and a plurality of drive/guideprojections projecting from the inner surface; wherein a spacing ofadjacent ones of traction projections in a longitudinal direction of thetrack is greater than a spacing of adjacent ones of the drive/guideprojections in the longitudinal direction of the track. 61.-188.(canceled)